Methods and apparatus for implementing and using a maximum rate option indicator

ABSTRACT

A base station selects a maximum rate option indicator value for an uplink communications segment, e.g., uplink traffic channel segment, and transmits the selected indicator value, e.g., as part of the assignment message. The maximum rate option indicator value indicates to the wireless terminal a maximum allowed data rate option that the wireless terminal is permitted to use for the corresponding assigned uplink communications segment, the wireless terminal determining the actual uplink rate option used. Each uplink data rate option corresponds to: a number of information bits to be communicated in an uplink communication segment, a coding rate, and a modulation method. Some embodiments include multiple types of maximum uplink rate option indicators, e.g., a first type using a single bit and a second type using at least three bits. Different modulation methods are, in some embodiments, used for communicating the different types of maximum uplink rate option indicators.

RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/659,502, filed on Mar. 8, 2005, titled “METHODAND APPARATUS FOR IMPLEMENTING AND USING AN UPLINK RATE INDICATOR”, U.S.Provisional Patent Application Ser. No. 60/701,469, filed on Jul. 20,2005, titled “METHODS AND APPARATUS FOR SIGNALING UPLINK DATA RATEOPTION INFORMATION”, U.S. Provisional Patent Application Ser. No.60/701,434, filed on Jul. 20, 2005, titled “METHODS AND APPARATUS FORWIRELESS TERMINAL UPLINK DATA RATE OPTION SELECTION”, and U.S.Provisional Patent Application Ser. No. 60/701,468, filed on Jul. 20,2005, titled “METHODS AND APPARATUS FOR IMPLEMENTING AND USING A MAXIMUMUPLINK RATE OPTION INDICATOR”, each of which is hereby expresslyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for improving theuplink communications for wireless communication devices, and moreparticularly to methods and apparatus for indicating and using uplinkrate information in a wireless communications system.

BACKGROUND OF THE INVENTION

In wireless communications systems, a wireless terminal often needs totransmit uplink user data and/or other information to a base station.The base station functions as a point of network attachment for thewireless terminal. In some known systems, at least some of the wirelessterminals are capable of transmitting uplink signals using differentuplink coding rates, resulting in different uplink transmission rates ofthe user data/information. For example, consider one exemplaryembodiment, where a wireless terminal is capable of transmitting uplinksignals corresponding to an uplink traffic channel segment usingdifferent coding rates. The same modulation scheme may be used, e.g.,quadrature phase shift keying (QPSK), and the same number of modulationsymbols may be communicated during the segment, conveying the samenumber of total bits, irrespective of the coding rate selected. However,at a low coding rate, the wireless terminal may use a relatively lowlevel of power and transmit a relatively small number of userdata/information bits per total bits and a relatively high number oferror correcting or redundant information bits per total number of bits.Conversely, at a high coding rate, the wireless terminal may use arelatively high level of power and transmit a relatively larger numberof user data/information bits per total number of bits and a relativelylow number of error correcting or redundant information bits per totalnumber of bits.

In some known wireless communications systems, at least some of thewireless terminals are capable of transmitting uplink signals usingdifferent modulation schemes, e.g., QPSK, BPSK (Bi-Phase Shift Keying)and/or Quadrature Amplitude Modulation (QAM), with different numbers ofbits being communicated on each modulation symbol depending of themodulation scheme used. Both the selected coding rate and the selectedmodulation scheme factor into the uplink data transmission rate. Theuplink data transmission rate, sometimes referred to as the uplink datarate, can be specified in terms of the number of data and/or informationbits per an uplink transmission unit. For example, the uplink data ratecan be specified as the number of data and/or information bits pertransmission symbol or the number of data/information bits per uplinksegment or the number of data/information frames per uplink segment. Anuplink segment in such a case is normally an uplink unit which can beused to transmit multiple symbols.

In some known systems, the base station assigns uplink traffic channelsegments and decides the uplink data transmission rate that the wirelessterminal should use which identifies the uplink coding rate, and ifdifferent modulation schemes are possible, the modulation scheme, thatthe wireless terminal should use. In such known systems, the mobilefollows the base station commanded uplink data rate and transmits uplinksignals accordingly without any discretion on the mobile's part. Thisapproach is not very efficient as the base station has limited knowledgeof the wireless terminal's condition at the time of uplink datatransmission rate assignment. In addition, conditions at the wirelessterminal can change from the time of uplink data transmission rateassignment to when the wireless terminal is ready to transmit on anassigned uplink traffic channel segment.

The base station can have reasonable knowledge of the overall levels ofinterference in the system and the potential levels of interference thata wireless terminal's uplink signals at a commanded data rate at a knownpower level can cause in the system. Indeed, a base station receivingfeedback reports from a plurality of WTs and controlling scheduling isgenerally in a much better position to evaluate system interferencelevels than an individual wireless terminal. However, the base stationhas an incomplete set of information as to determine what uplink datarate the wireless terminal should use at the time of its uplinktransmission. Some contributing factors can be better measured and/orevaluated by the wireless terminal.

The base station can have an estimate of the amount of data to betransmitted on the uplink by a given wireless terminal. However, thewireless terminal knows the actual amount of information that needs tobe transmitted at the time the assigned uplink traffic segment messagesare coded. For example, the base station may be unaware of new user datathat has arrived subsequent to a wireless terminal request message, orthe base station may be unaware of buffered user data that has beensubsequently dropped following a wireless terminal request message.Typically, this results in operational inefficiencies. For example, if awireless terminal has been commanded to use a higher data rate than itactually needs, the wireless terminal typically pads the extra (empty)information locations with zero's and transmits at the relatively highpower level associated with the high data rate. This results in thewireless terminal unnecessarily consuming valuable battery energy andcreating a higher level of interference in the system than if it hadtransmitted at the lower data rate which would have satisfied its needs.Conversely, if the base station had commanded the wireless terminal touse a low data rate because its estimate of the data uplink requirementswas low; however, if requirements changed subsequent to the wirelessterminal's request but prior to the wireless terminal uplink trafficchannel segment message coding/modulation, the wireless terminal couldend up communicating fewer user data/information bits (ordata/information frames) in the uplink traffic channel segment thanwould have been possible at a higher data rate. This contributes tolatency delays in the system.

In addition, the wireless terminal typically has better and more currentinformation as to its battery power level, transmission power availablefor data and other signal transmission after a portion of thetransmission power is allocated to a particular set of signals, e.g.,control channels, operational drain, and operational power needs thanthe base station. The wireless terminal also typically has betterknowledge of changes in the channel conditions, e.g., changes due to thewireless terminal moving or changes in the rate of movement, thewireless terminal entering a tunnel, the wireless terminal moving from arural to city environment, etc., than the base station. In many cases itis not practical, effective, or convenient to convey such information toa base station, e.g., either from an overhead standpoint or from a timelatency standpoint or such information to the extent that it is conveyedis somewhat out of date by the time it arrives at the base station.

In view of the above discussion, it is apparent that neither the basestation nor the wireless terminal normally has the complete set ofinformation on factors which influence the best choice of uplink datatransmission rate for a wireless terminal to use. It would beadvantageous if new methods and apparatus were developed which allowedfor both the base station and wireless terminal to participate in theselection of the uplink data rate to be used by the wireless terminal.

SUMMARY OF THE INVENTION

A base station operates in a communications system to transmitassignment information of uplink communications segments, e.g., uplinktraffic channel segments, each segment having a predetermined duration.The base station transmits over a wireless communications channel anassignment including a maximum uplink rate option indicator indicating amaximum uplink rate option to be used by a wireless terminal indetermining the actual uplink transmission rate to be used whentransmitting in a communications segment corresponding to theassignment. In some embodiments, the communications segments are OFDMcommunications segments, e.g., OFDM uplink traffic channel segments,including multiple tones used for a plurality of OFDM symboltransmission time periods. In some embodiments, each of the uplinktraffic channel segments includes the same number of basic transmissionunits, e.g., the same number of tone-symbols. In various embodiments,the system, e.g., an OFDM spread spectrum multiple access wirelesscommunications system, supports a fixed number of different uplink rateoptions. For example, each of the different uplink rate optionscorresponds to a different number of information bits and/or number offrames to be communicated in a communications segment, and each uplinkrate option also corresponds to at least one of a coding rate andmodulation method to be used.

In various embodiments, the base station selects a maximum rate optionindicator value, e.g., corresponding to an assigned uplinkcommunications segment, and then transmits the selected value to thewireless terminal, e.g., as part of an assignment message. In otherembodiments, the maximum uplink rate option indicator valuecorresponding to an uplink communications segment is communicatedindependently of the assignment. The selected value is, in someembodiments, selected from a set of values including at least the valuecorresponding to the highest uplink rate option supported by the systemand another value corresponding to an intermediate uplink rate optionsupported by the system.

In some embodiments, a plurality of types of maximum uplink rate optionindicators are used in the system. For example, an exemplary uplinktiming and frequency structure uses a fixed number of indexed uplinktraffic channel segments which repeat on a recurring basis, and a firstset of the indexed uplink traffic channel segments are associated with afirst type of maximum uplink rate option indicator, while a second setof the indexed uplink traffic channel segments are associated with asecond type of uplink rate option indicator, where the first and secondsets are disjoint sets. In various embodiments, a first type of maximumuplink rate option indicator includes a first number of bits while asecond type of maximum uplink rate option indicator includes a secondnumber of bits, the second type of maximum uplink rate option indicatorincludes more bits than the first type of maximum uplink rate optionindicator allowing for more uplink rate options to be specified whenusing a second type indicator than when using a first type indicator. Insome embodiments, the first type indicator includes at most one bit andthe second type indicator includes at least three bits.

The base station, in various embodiments, stores rate option indicatortables, e.g., first and second maximum rate option indicator tables, anduses the first table for first type indicator assignments and uses thesecond table for second type indicator assignments. In some suchembodiments, the second table includes each supported uplink rateoption.

In some embodiments, using first and second types of maximum rate optionindicators, different modulation methods are used to transmit first andsecond maximum uplink rate option indicator values. For example, someembodiments use a first type maximum uplink rate option indicator whichis communicated as part of a first type of assignment, e.g., a flashassignment, using a non-coherent modulation method such as, e.g., amodulation method using a combination of zero and non-zero QPSKmodulation symbols, while a second type of maximum uplink rate optionindicator is communicated as part of a second type of assignment, e.g.,a regular assignment, using a coherent modulation method using QPSKmodulation symbols. In some such embodiments, the non-zero modulationsymbols of the first type of assignments are communicated using a higherpower level than the modulation symbols of the second type ofassignment.

In various embodiments, the base station transmits assignments includingmaximum rate indicators according to a predetermined periodictransmission schedule having a fixed timing relationship to the uplinksegments being assigned. In some embodiments, each first type of maximumuplink rate option indicator is communicated in an assignment messageincluding at most one uplink communication segment assignment, while asecond type of maximum rate option indicator is communicated incommunicated in an assignment message including one or more, e.g., two,maximum uplink communications segment assignments, e.g., with eachseparate assigned uplink communications segment having a correspondingseparate uplink rate option indicator.

While various embodiments have been discussed in the summary above, itshould be appreciated that not necessarily all embodiments include thesame features and some of the features described above are not necessarybut can be desirable in some embodiments. Numerous additional features,embodiments and benefits of the present invention are discussed in thedetailed description which follows.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a drawing of an exemplary communications system, implementedin accordance with the present invention and using methods of thepresent invention.

FIG. 2 is a drawing of an exemplary base station, implemented inaccordance with the present invention and using methods of the presentinvention.

FIG. 3 is a drawing of an exemplary wireless terminal, implemented inaccordance with the present invention and using methods of the presentinvention.

FIG. 4 is a drawing illustrating exemplary base station maximum uplinkdata rate indicator levels and exemplary corresponding uplink data ratelevels that may be selected and used by a wireless terminal.

FIG. 5 is a drawing illustrating that an uplink data rate used by awireless terminal can be conveyed in parallel with uplink user data byconcentrating additional energy on one tone of the dwell, in accordancewith the present invention.

FIG. 6 is a drawing illustrating exemplary uplink traffic channelsegments in a wireless communications system.

FIG. 7 is a table illustrating exemplary rate options available to awireless terminal for an uplink traffic segment.

FIG. 8 is a drawing illustrating an exemplary uplink traffic segment,and the concentration of additional energy on a subset on tone-symbolswithin the dwell to convey the uplink data rate used for the segment, inaccordance with the present invention.

FIG. 9 is a flowchart of an exemplary method of operating a base stationin accordance with the present invention.

FIG. 10 is a flowchart of an exemplary method of operating a wirelessterminal in accordance with the present invention.

FIG. 11 is another example of exemplary data rate options available toan exemplary wireless terminal for an uplink traffic segment, andexamples of corresponding maximum uplink data rate indicators, inaccordance with the present invention.

FIG. 12 is another example of exemplary data rate options available toan exemplary wireless terminal for an uplink traffic segment, andexamples of corresponding maximum uplink data rate indicators, inaccordance with the present invention.

FIG. 13 is a table illustrating another set of exemplary data rateoptions available to a wireless terminal for an uplink traffic segment.

FIG. 14 is a drawing illustrating an exemplary uplink traffic segment,and the partitioning of the segment into a subset of tone-symbols toconvey the uplink data rate used for the user data/info signals of thesegment and a subset of tone-symbols used to convey userdata/information, in accordance with some embodiments the presentinvention.

FIG. 15 includes tables illustrating exemplary embodiments in which thewireless terminal selected uplink data transmission rate may becommunicated by a power difference placed on a subset of symbols of theuplink segment, and the power difference may be a fixed value or may bea value which is a function of the selected data rate in terms of dBabove the power level used to communicate the user data/informationmodulation symbol.

FIG. 16 is a drawing illustrating an exemplary uplink traffic segmentincluding tone-symbols used to convey modulation symbols conveyinginformation bits and tone-symbols used to convey reference modulationsymbols, and the concentration of additional energy on a subset ontone-symbols within the dwell to convey the uplink data rate used forthe segment, in accordance with the present invention.

FIG. 17 is a table illustrating an exemplary relationship between basestation selected maximum rate indicators and data rates that a wirelessterminal can select in another exemplary embodiment of the presentinvention.

FIG. 18 is a drawing illustrating a portion of an exemplary uplinktraffic segment, and the concentration of additional energy on a subsetof tone-symbols within the dwell to convey the uplink data rate used forthe segment, in accordance with an exemplary embodiment of the presentinvention.

FIG. 19 is a drawing illustrating a portion of an exemplary uplinktraffic segment including tone-symbols used to convey modulation symbolsconveying information bits and tone-symbols used to convey referencemodulation symbols, and the concentration of additional energy on asubset on tone-symbols within the dwell to convey the uplink data rateused for the segment, in accordance with the present invention.

FIGS. 20-22 are drawing of different types of exemplary uplink trafficchannel segments, in accordance with the present invention.

FIG. 23 is a table of exemplary uplink traffic channel rate options andcorresponding sets of information for each rate option including codingrate and modulation type information, in accordance with variousembodiments of the present invention.

FIG. 24 is a table illustrating exemplary mapping between an uplinktraffic channel segment in-band indicator X and uplink traffic channelrate option values, in accordance with various embodiments of thepresent invention.

FIG. 25 includes a drawing of an exemplary tone-halfslot of index k, inaccordance with the present invention.

FIG. 26 illustrates an exemplary uplink traffic channel segment in whichthe WT has selected to use uplink traffic channel rate option 0 andconveys that selection via a mapped modulation symbol scaling pattern.

FIG. 27 illustrates an exemplary uplink traffic channel segment in whichthe WT has selected to use uplink traffic channel rate option 2 andconveys that selection via a mapped modulation symbol scaling pattern.

FIG. 28 illustrates an exemplary uplink traffic channel segment in whichthe WT has selected to use uplink traffic channel rate option 5 or 6 andconveys that selection via a mapped modulation symbol scaling patternsignifying that the uplink traffic channel in-band rate indicator Xequals 5.

FIG. 29 includes tables illustrating different types of uplink trafficchannel assignment signaling techniques and information conveyed, inaccordance with the present invention.

FIG. 30 illustrates exemplary QPSK constellation mapping and exemplaryQAM16 constellation mapping tables.

FIG. 31 illustrates exemplary assignment and exemplary correspondinguplink traffic channel segments.

FIG. 32 is a flowchart of an exemplary method of operating a wirelessterminal in a wireless communications system, in accordance with thepresent invention.

FIG. 33 is a drawing of an exemplary wireless terminal, e.g., mobilenode, implemented in accordance with the present invention and usingmethods of the present invention.

FIG. 34 comprising the combination of FIG. 34A and FIG. 34B is aflowchart of an exemplary method of operating a wireless terminal inaccordance with the present invention.

FIG. 35 is a drawing of an exemplary wireless terminal, e.g., a mobilenode, implemented in accordance with the present invention and usingmethods of the present invention.

FIG. 36 is a flowchart illustrating an exemplary method, in accordancewith the present invention, of operating a base station in acommunications system to generate and transmit assignment informationindicating the assignment of uplink communications segments, each uplinkcommunications segment having a predetermined duration.

FIG. 37 is a drawing of an exemplary base station implemented inaccordance with the present invention and using methods of the presentinvention.

FIG. 38 is a flowchart of an exemplary method of operating a wirelessterminal in a wireless communications system, in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a drawing of an exemplary communications system 100,implemented in accordance with the present invention and using methodsof the present invention. System 100 includes apparatus and methodsdirected to improving uplink communications by selecting andcommunicating uplink data rate information. Exemplary system 100 may be,e.g., an orthogonal frequency division multiplexing (OFDM) multipleaccess wireless communication system. System 100 includes a plurality ofcells (cell 1 102, cell M 104). Each cell (cell 1 102, cell M 104)represents a wireless coverage area for a corresponding base station (BS1 106, BS M 108), respectively. A plurality of wireless terminal (WTs)(WT 1 110, WT N 112, WT 1′ 114, WT N′ 116) are included in system 100.At least some of the WTs are mobile nodes (MNs); the MNs may movethroughout the system 100 and establish wireless links with differentBSs, the BS corresponding to the cell in which the WT is currentlylocated. In FIG. 1, (WT 1 110, WT N 112) are coupled to BS 1 106 viawireless links (118, 120), respectively; (WT 1′ 114, WT N′ 116) arecoupled to BS M 108 via wireless links (122, 124), respectively.

The BSs (106, 108) are coupled to network node 126 via network links(128, 130), respectively. Network node 126 is coupled to other networknodes, e.g., routers, other base stations, AAA server nodes, Home Agentnodes, etc. and/or the Internet via network link 132. Network links 128,130, 132 may be, e.g., fiber optic links. Network node 126 and networkslinks 128, 130, 132 are part of a backhaul network linking various BSsin different cells together and providing connectivity so that a WTlocated in one cell can communicate with a peer node in a differentcell.

System 100 is shown having cells with one sector per cell. The methodsand apparatus of the present invention are also applicable in systemshaving more than one sector per cell, e.g., 2, 3, or more than 3 sectorsper cell and in systems having different numbers of sectors per cell indifferent portions of the system. In addition, the methods and apparatusof the present invention are also applicable to many non-cellularwireless communications systems including at least one base station andone wireless terminal.

FIG. 2 is a drawing of an exemplary base station 200, implemented inaccordance with the present invention and using methods of the presentinvention. Exemplary BS 200 is sometimes referred to as an access node.BS 200 may be any of the BS (106, 108) of system 100 of FIG. 1.Exemplary BS 200 includes a receiver 202, a transmitter 204, a processor206, I/O interface 208, and memory 210 coupled together via a bus 212over which the various elements may interchange data and information.

Receiver 202 is coupled to receive antenna 203 through which BS 200 mayreceive uplink signals from a plurality of wireless terminals. Receiver202 includes a decoder 214 for decoding received encoded uplink signals.Received encoded uplink signals include uplink traffic channel signalsincluding user data/information and data rate used information.

Transmitter 204 is coupled to transmit antenna 205 over which downlinksignals are sent to a plurality of wireless terminals. Transmitter 204includes an encoder 216 for encoding information prior to transmission.Downlink signals include assignments of dedicated uplink traffic channelsegments and corresponding maximum uplink data rate indicator signals.

I/O interface 208 couples the BS 200 to other network nodes, e.g.,routers, other base stations, AAA server nodes, Home Agent nodes and/orthe Internet. I/O interface 208 provides an interface to a backhaulnetwork providing interconnectivity between nodes in different cells.

Memory 210 includes routines 218 and data/information 220. The processor206, e.g., a CPU, executes the routines 218 and uses thedata/information 220 in memory 210 to operate the BS 200 and implementmethods of the present invention.

Routines 218 include communications routines 222 and base stationcontrol routines 224. The communications routines 222 implement variouscommunications protocols used by BS 200.

The base station control routines 224 control the operation of BS 200including receiver 202 operation, transmitter 204 operation, I/Ointerface 208 operation, and the implementation of methods of thepresent invention. Base station control routines 224 include ascheduling module 226, a channel quality determination module 228, awireless terminal interference estimation module 230, an uplink datatransmission estimation module 232, a maximum uplink data rate selectionmodule 234, a wireless terminal uplink data rate used determinationmodule 236, a downlink signaling module 238, and an uplink signalingmodule 240.

The scheduling module 226, e.g., a scheduler, schedules uplink anddownlink channel air link resources, e.g., segments, to wirelessterminal users. Scheduler 226 operations include assigning uplinktraffic channel segments to specific wireless terminals from a pluralityof wireless terminal. Different uplink traffic channel segments may havedifferent characteristics, e.g., more tones for a shorter duration orfewer tones for a longer duration, and the scheduler may take thesedifferences into consideration when deciding which uplink trafficsegment should be assigned to which user. Scheduler 226 may assign anumber of uplink traffic channel segments to a wireless terminal at apoint in time based upon an estimate of the amount of data to betransmitted by the WT 300. Each tone may be used to communicate a signalduring an OFDM symbol transmission time period.

Channel quality determination module 228 determines, for each WT 300under consideration, communications channel quality between the basestation 200 and wireless terminal 300, e.g., based on received channelquality reports 292 from WT 300 and evaluated received uplink signalsfrom WT 300. In some embodiments, the channel quality reports 292 arebased upon WT 300 measurements of received known signals, e.g., pilotsignals, beacon signals, etc., communicated as downlink signals from BS200 to WT 300, and it is assumed that uplink channel quality correspondsto downlink channel quality.

Wireless terminal interference estimation module 230 estimates, for eachWT 300 under consideration, the interference that will be caused toother wireless terminals if a specific wireless terminal 300 transmitsuplink signals using one or more different uplink data rates.

Uplink data transmission estimation module 232 estimates, for each WT300 under consideration, the amount of data that the wireless terminal300 needs to transmit to the base station. The uplink data transmissionestimation module 232 can base its estimation on things such as:received resource requests, unfulfilled received resource requests,previously allocated uplink traffic channel segments, an ack/nak ratioin response to received uplink traffic channel segment signals, uplinkrate previously selected for use by the wireless terminal, type ofwireless terminal, e.g., data terminal, voice cellular device,voice/video/messaging cellular device, etc., type of uplink signaling,e.g., voice, data, video, etc., service plan, and/or historical usageinformation corresponding to the WT 300.

Maximum uplink data rate selection module 234 selects a maximum uplinkdata transmission rate to be used by a WT 300 when transmitting uplinksignals to the BS 200 on a corresponding assigned uplink traffic channelsegment, said selected maximum uplink data transmission rate being one aplurality of possible transmission data rates. Maximum uplink data rateselection module 234 selects, for each assigned uplink traffic channelsegment, a maximum data rate that the WT assigned the uplink trafficsegment should use. Maximum uplink data rate selection module 234 basesits selection upon: the estimated quality of the wireless communicationschannel, the interference estimates, and/or received battery informationcorresponding to the WT 300.

WT uplink data rate used determination module 236 determines an uplinkdata transmission rate selected and utilized by the WT 300 for theuplink traffic channel segment from the received signals conveyed in theuplink traffic channel segment. In some embodiments, the utilized uplinkdata rate information is indicated by the location of additional energybeyond the energy used to communicate data on a predetermined subset ofone or more signals used to communicate the data in the uplink trafficchannel segment. Different subsets of signals having the additionalenergy can correspond to different possible data rates that could havebeen selected and used by the WT.

Downlink signaling module 238 controls operation of the transmitter 204and its encoder 204 to transmit downlink signals including uplinktraffic segment assignment information and associated maximum uplinkdata rate indicator, the base station selected maximum uplink datatransmission rate to be used by the WT 300 assigned the uplink trafficchannel segment.

Uplink signaling module 240 controls operations of receiver 202 and itsdecoder 214 to receive and process uplink signals including: resourcerequests, channel quality reports, battery indicator messages and uplinktraffic channel signals from a plurality of WTs. The uplink signalingmodule 240 also forwards each determined uplink data transmission rate,e.g., identifying coding rate information and/or modulation typeinformation, from module 236 to decoder 214 to be used to recoveruser/data information conveyed in the corresponding uplink trafficchannel segment signals.

Data/information 220 includes a plurality of sets of WT data/information244 (WT 1 data/info 246, WT N data info 248) and system data/information270. WT 1 data/information 246 includes user data 250, WT identificationinformation 252, device/session/resource information 254, channelquality information 256, uplink interference estimate information 258,estimated amount of uplink transmit data 260, battery status information262, maximum uplink data rate indicator information 264, uplink assignedsegment information 266, and uplink data rate used information 268.

User data 250 includes user data/information such as e.g., data/inforepresenting voice, text or video, received on uplink traffic channelsegments from WT 1 intended to be forwarded to a peer node of WT 1 in acommunications session with WT 1. User data 250 may also include userdata/information sourced from a peer node of WT 1 to be communicated toWT 1 via downlink traffic channel segment signals.

WT identification information 252 includes, e.g., a base stationassigned active user identifier and an IP address associated with WT 1.Device/session/resource information 254 includes uplink and downlinksegments, e.g., traffic channel segments, assigned to WT 1 by schedulingmodule 226 and session information including address and routinginformation pertaining to peer nodes of WT1 in communication sessionswith WT 1.

Channel quality information 256 includes information obtained or derivedfrom a received channel quality report 292 from WT 1 and channel qualityinformation determined from measurements and evaluation of uplinksignals from WT1. Channel quality information 256 is an output ofchannel quality determination module 228 and is used as an input tomaximum uplink data rate selection module 234.

Uplink interference estimation information 258 includes base stationestimates of the potential interference levels that WT1 is expectedgenerate to other WTs if WT1 transmits uplink signals at various uplinktransmission rates being considered for selection by the BS as themaximum uplink data transmission rate. Uplink interference estimationinformation 258 is an output of module 230 and an input to module 234.

Estimated amount of uplink transmission data 260 is a BS 200 estimate,using information currently available to BS 200, of the current uplinkdata transmission needs of WT1. Estimated amount of uplink transmissiondata 260 may be used by scheduling module 266 in determining the numberof uplink traffic channel segments to assign to WT1.

Power status information 262 includes information pertaining to WT1extracted from received power indicator messages 293. The powerindicator messages 293 may provide information on remaining batterypower and/or information referred to sometimes herein as backoff powerinformation. Backoff power information indicates the amount oftransmission power available after the allocation of power to a set ofsignals, e.g., a predetermined signals corresponding to one or morecontrol channels, e.g., corresponding to a dedicated control channel(DCCH), which are subject to power control from the base station. Thepower control may be, e.g., a closed loop power control process. Thetotal amount of output transmission power for the WT may be limited bylaw or other constraints, e.g., battery power, such that after the WTallocates power to a predetermined set of signals there is a limitedamount of transmission power available for the transmission of othersignals, e.g., user data. The allocation of the power to thepredetermined set of signals may be performed under direction of one ormore control signals from the base station instructing the WT toincrease or decrease the amount of power used to transmit thepredetermined signals. In some embodiments, the base station measuresone or more received signals in the set of predetermined signals andinstructs the WT to adjust the power level of the predetermined signalsto increase or decrease the transmission power dedicated to thepredetermined set of signals. While the base station may instructchanges in the transmission power dedicated to the predetermined set ofsignals, all the power control commands may not be received making itdifficult for the base station to know the actual amount of transmissionpower dedicated by the WT to the transmission of the predetermined setof signals. The backoff power information provides the base station withan indication of the amount of power available at the WT sending thebackoff power signal for transmitting signals other than thepredetermined set of signals. From the backoff power signal, in caseswhere the base station knows the WTs total transmission power which canbe used, either because it is fixed or reported to the base station, thebase station can determine not only the amount of power available fortransmission of signals other than the predetermined set of signals butalso the amount of power allocated to the predetermined set of signals.The amount of power available for signals other than the predeterminedset of signals is used by the base station in some embodiments inselecting the maximum transmission rate allowed to be used by aparticular WT for uplink signaling at a particular point in time.

An indication of the amount of available power for transmitting signalsother than the predetermined set of signals and/or available batterypower can be, and in various embodiments are, considered by maximumuplink data rate selection module 234 in selecting the maximum allowableuplink data rate for the WT1 uplink traffic channel segment. Forexample, the amount of available transmission power may limit themaximum data rate possible with the base station selecting a maximumdata rate option which can be supported given the power believed to beavailable at the WT for the transmission of data signals. As the amountof power available for transmitting signals other than saidpredetermined set of signals declines, lower data rate options may beselected as the maximum permitted uplink data rate option whileincreases in available transmission power may result in a maximumpermitted uplink data rate option corresponding to higher data ratesbeing selected for the wireless terminal reporting the increased amountof available power.

Maximum uplink data rate indicator information 264 is an output of themaximum uplink data rate selection module 234 and indicates the basestation selected maximum uplink data transmission rate which is themaximum uplink data transmission rate WT1 is permitted to use whentransmitting uplink signals on the assigned corresponding uplink trafficchannel segment. In some embodiments, the maximum uplink data rateindicator includes, at most, a maximum number of bits that is less thanthe number of bits required to uniquely specify the full set of uplinkdata transmission rates which can be used by WT1. Maximum uplink datarate indicator information 264 is included in a maximum uplink data ratemessage 296 transmitted via the control of downlink signaling module 238by BS 200 to WT1.

Uplink assigned segment information 266 includes information identifyinguplink traffic channel segments assigned to WT1, encodeddata/information conveyed in such segments, and data/informationrecovered from such segments including frames of user data. Uplink datarate used information 268 includes the WT selected and utilized uplinkdata transmission rate in each of uplink traffic channel segmentsassigned to WT1. Uplink data rate used information 268 may includecoding rate information and/or modulation scheme information. Uplinkdata rate used info 268 is an output of WT UL data rate determinationmodule 236 and is used by decoder 214 in the recovery of userdata/information.

System data/information 270 includes uplink/downlink timing andfrequency structure information 272, maximum selected uplink data rateinformation 274 and uplink data rate used information 276.Uplink/downlink timing and frequency structure information 272 includes,e.g., symbol timing information, tone spacing information, number ofuplink tones, number of downlink tones, uplink carrier frequency,downlink carrier frequency, uplink bandwidth, downlink bandwidth, uplinkset of tones, downlink set of tones, uplink tone hopping information,uplink dwell information, downlink tone hopping information, downlinktraffic segment structure information, uplink traffic segment structureinformation, repetitive timing structures, e.g., symbol time intervalsand grouping of symbol time intervals into, e.g., dwells, half-slots,slots, superslots, beacon slots, ultra slots, etc.

Maximum selected uplink data rate information 274 includes a pluralityof sets of data rate information (rate 1 info 278, rate M information280), selection criteria 282, and encoding information 284. Each set ofrate info (278, 280) corresponding to one of the potential data ratesthat may be selected by BS 200 module 234 to be indicated as a maximumuplink data transmission rate. Each set of data rate info (278, 280) mayinclude or correspond to a coding rate and/or a modulation scheme.Selection criteria 282 includes predetermined limits and values used bymodule 234 in determining the max selected uplink data rate, e.g., SNRreference levels, SIR reference levels and/or rate back-off amountsassociated with received low battery level indication information.

Encoding information 284 includes information used to encode the BSselected maximum uplink data rate indicator into a message to besignaled to the WT assigned the corresponding uplink traffic channelsegment. In some embodiments, the max uplink data rate indicator isincluded in the uplink traffic channel assignment message, while inother embodiments it is included in a different downlink message. Insome embodiments, a wireless terminal is assigned a maximum uplink datatransmission rate on a per uplink traffic channel segment basis or groupof traffic channel segments, e.g., assigned at any one time. In otherembodiments, a WT may be assigned a maximum uplink data transmissionrate which remains in effect until the BS signals a new maximum uplinkdata transmission rate.

Uplink data rate used information 276 includes a plurality of sets ofdata rate information (rate 1 information 286, rate N information 288)and data rate determining information 290. Each set of data rateinformation (286, 288) corresponds to a possible uplink data rate whichcan be used by a WT 300 for transmission of uplink traffic channelsegment signals. Each uplink data rate can correspond to a coding rateand/or a modulation scheme. Data rate determining information 290includes information used by module 236 to decode the uplink rateselected and used during an uplink traffic channel segment by a WT 300.Data rate determining information 290 can include, e.g., sets oflocations within a segment or patterns within the segment identifyingwhere additional energy has been allocated to specific tones duringspecific symbol transmission times of the segment, each different setcorresponding to a different uplink data rate that may have beenselected by WT 300.

In some embodiments, different sets of information 274 and 276 may existfor different wireless terminals or different types or classes ofwireless terminals. For a given wireless terminal, the number M of maxselected uplink data rates (278,280) is less than or equal to the numberN of uplink data rates used (286, 288). In some embodiments, for atleast some wireless terminals, the number of max selected uplink datarates M (278,280) is less than the number N of uplink data rates used(286, 288).

Data/information 220 also includes received channel quality reports 292,e.g., feedback reports of measured channel conditions, received powerindicator messages 293, e.g., transmission power back-off signals and/orbattery power signals, received uplink resource request messages 294,e.g., requests for an uplink traffic channel segment or segments andreceived uplink traffic channel segments 297, said received messages292, 293, 294, 297 being sourced from a plurality of WTs 300. Thereceived uplink traffic channel segment messages 297 include user data298 and data rate information 299, the user data 298 having beencommunicated using the coding rate and/or modulation scheme indicated bythe rate information 299. Data/information 220 also includes, in theexemplary embodiment, uplink segment assignment messages 295, e.g.,assignments of dedicated uplink traffic channel segments to specific WTsand maximum uplink data rate messages 296 conveying maximum data rateindicators to WTs. In some embodiments maximum uplink data rate messageinformation is included as part of uplink segment assignment messages.

FIG. 3 is a drawing of an exemplary wireless terminal 300, implementedin accordance with the present invention and using methods of thepresent invention. WT 300 may be any of the WTs (110, 112, 114, 116) ofsystem 100 of FIG. 1. Exemplary WT 300 includes a receiver 302, atransmitter 304, a processor 306, user I/O devices 308, and memory 310coupled together via a bus 312 over which the various elements mayinterchange data and information.

Receiver 302 is coupled to receive antenna 303 through which WT 300receives downlink signals from BS 200 including assignments for uplinktraffic channels and maximum uplink data rate indicator signals.Receiver 302 includes a decoder 314 which is used by WT 300 to decodereceived downlink signals from BS 200.

Transmitter 304 is coupled to transmit antenna 305 through which WT 300transmits uplink signals to BS 200 including channel quality reports,power indication signals, uplink resource request messages, and uplinktraffic channel segment signals including user data and data rateinformation. In some embodiments, the same antenna is used as both thetransmit antenna 305 and the receive antenna 303. Transmitter 204includes an encoder 316 for encoding uplink data/information prior totransmission.

User I/O devices 308 includes, e.g., microphones, speakers, keypad,keyboard, mouse, touch-screen, camera, displays, alarms, vibrationdevice, etc. Various user I/O devices 308 are used to input userdata/information intended for peer nodes of WT 300 and to outputreceived data/information from peer nodes of WT 300. In addition, userI/O devices 308 are used by an operator of WT 300 to initiate variousfunctions, e.g., power on, power off, place a call, terminate a call,etc.

Memory 310 includes routines 318 and data/information 320. The processor306, e.g., a CPU, executes the routines 318 and uses thedata/information 320 in memory 310 to control the operation of WT 300and implement the methods of the present invention.

Routines 318 include a communications routine 322 and wireless terminalcontrol routines 324. The communications routine 334 implements thevarious communications protocols used by the WT 300. The wirelessterminal control routines 324 control operations of WT 300 including theoperation of receiver 302, transmitter 304, and user I/O devices 308.Wireless terminal control routines 324 includes a power monitor module326, a channel variation detection module 328, a maximum base stationallowed data rate determination module 330, an uplink data rate usedselection module 332, an uplink data rate used encoding module 334, adownlink signaling module 336, and an uplink signaling module 338.

Power monitor module 326 monitors the amount of power available fortransmitting signals after transmission power is allocated to a set ofsignals, e.g., a predetermined set of control channel signals. Themodule 326 may also monitor the status of the WT's battery, e.g., energylevel and current rate of energy level decline or increase, andestimates remaining battery power. Estimated power information 354, anoutput of power monitor module 326 is used by the uplink data rateselection module 332 in determining the actual uplink data rate to beused for transmitting signals, e.g., user data signals. In someembodiments, estimated power info 354 also includes informationindicative as to whether the wireless terminal 300 is currentlyoperating on its own battery reserve or an external power source, e.g.,a car's electrical system, in which case the power used for currentuplink signaling will not further deplete the battery. In addition, thepower monitor module 326, in some embodiments, generates power indicatormessages 388, e.g., WT power back-off messages and or battery powerinformation messages to BS 200.

Channel variation detection module 328 measures channel quality, e.g.,based on received known signals, e.g., pilot signals, beacon signals,etc. communicated from BSs 200 over the downlink and generates channelquality reports 386, e.g., periodically, which are subsequentlycommunicated to a BS 200. The channel quality information 350, an outputof module 328, made available to uplink data rate used selection module332, is generally updated more frequently than the channel qualityreports 386, thus providing WT 300 with more current information at anygiven time to make a better decision as to the uplink data rate to use.In addition, the channel variation detection module 328 detects changesin channel quality and/or changes in operating conditions and/orenvironment which can be expected to change the channel quality. Channelquality information 350 including detected change information 352 ismade available to the uplink data rate used selection module 332. Changevariation detection module 328 can detect changes due to factors such asa change in wireless terminal 300 velocity, e.g., as a wireless terminalchanges from a static device to a moving device, or a change inenvironments, e.g., a WT moves from a rural to a city environment, a WTenters a tunnel, etc. Such variations may be detectable by the WT andsuch information may be useful in making decisions as to which uplinkdata rate to use. In many embodiments, it may be inefficient tocommunicate such change information to the BS 200 for use in WT 300uplink maximum data rate selection and/or time constraints associatedwith the validity of such information may make it impractical. However,such change information can be, and is used, in some embodiments, by thewireless terminal's uplink data rate used selection module 332.

Maximum base station allowed data rate determination module 330processes received signals conveying a maximum uplink data rateindicator, e.g., a received maximum uplink data rate message 394. Insome embodiments, the maximum uplink data rate indicator may be conveyedin a different message, e.g., a received uplink segment assignmentmessage 392. Module 330 uses information 320 including data ratedetermining information 374, e.g., data rate level decoding information,to determine the received maximum allowable uplink data rate 358,corresponding to at least some uplink traffic channel segments assignedto WT 300, from a plurality of potential maximum uplink data ratescorresponding to information (370, 372).

Uplink data rate selection module 332 determines the selected uplinkdata transmit rate 362 to use for assigned uplink traffic channelsegments identified in uplink assigned segment information 360. Eachdata rate may correspond to a coding rate and/or modulation scheme.Uplink data rate selection module 332 uses data/information 320including the amount of uplink user data to transmit 356, the importancelevel of the information to transmit 342, the estimated powerinformation 354, channel quality information 350 including detectedchange information 352, and data rate selection criteria 382 to select aselected uplink data transmit rate 362 less than or equal to thereceived maximum allowed uplink data rate 358 from among the potentialuplink data rates supported by WT 300 identified in info (378,380).

Uplink data rate used encoding module 334 uses the data/info 320including encoding information 384 to encode the selected uplink datatransmit rate 362 for a given uplink traffic channel segment along withthe user data/info to be communicated in the uplink traffic channelsegment. In some embodiments, the encoding information 384 specifiessubsets of locations (within a set of locations of the time/frequencygrid corresponding to an uplink traffic channel segment) to haveadditional energy placed thereon beyond the energy used to communicatethe data, different subsets of locations for the same uplink trafficchannel segment corresponding to different uplink data rates used tocommunicate the data. In some embodiments, the additional energy is atleast 2 dB above the energy used to transmit the data. In someembodiments, using a dwell uplink structure and uplink segments, one ofthe symbol transmission time intervals of each dwell of the uplinksegment, e.g., the first symbol time interval of the dwell, is used toconvey a subset of signals with additional energy; a sequential patternof tones selected to convey the additional energy on the subset ofsignals during the uplink segment being used to convey the data rateused, different patterns corresponding to different data rates.

Downlink signaling module 336 controls operation of the receiver 302 anddecoder 304 to receive and process downlink signals from a BS 200, saiddownlink signals including uplink traffic channel segment assignmentmessages 392 and maximum uplink data rate indicator messages 394.

Uplink signaling module 338 controls the operation of transmitter 304and encoder 316 to encode and transmit uplink signals to BS 200, saiduplink signals including channel quality reports 386, power indicatormessages 388, uplink resource request messages 390 and uplink trafficchannel segment messages 396. The uplink traffic channel segmentmessages 396 include user data 398 and data rate information 399.

Data/information 320 includes WT data/info 339, system data/information364, channel quality reports 386, e.g., feedback reports of measuredchannel conditions, power indicator messages 388, e.g., transmissionpower back-off signals, uplink resource request messages 390, e.g.,requests for an uplink traffic channel segment or segments, receiveduplink segment assignment messages 392, e.g., assignments of dedicateduplink traffic channel segments to WT 300, received maximum uplink datarate messages 394 conveying maximum data rate indicators to WT 300 anduplink traffic channel segment message information 396. The uplinktraffic channel message information 396 includes user data 398 andcorresponding data rate information 399. The uplink traffic channelmessage information 396 is transmitted using assigned uplink trafficsegments via transmitter 304 under the control of uplink signalingmodule 338 to BS 200.

WT data/information 339 includes user data 340, importance levelinformation 342, WT identification (ID) information 344, base station IDinformation 346, device/session/resource information 348, channelquality information 350 including detected change information 352, powerinformation 354, amount of uplink transmit data 356, received maximumallowable uplink data rate 358, uplink assigned segment information 360,and selected uplink data transmit rate 362. User data 340 includesdata/information intended for a peer of WT 300 in a communicationssession with WT 300 and transmitted by WT 300 to BS 200 over uplinktraffic channel segments. User data 340 also includes data/informationsourced from a peer of WT 300 in a communications session with WT 300and received from BS 200 via downlink traffic segments.

Importance level information 342 includes information associated withdifferent portions of uplink user data to be transmitted identifying theimportance of the portions of data, e.g., in terms of priority,application, urgency to transmit, etc. Different applications and/orpeers may be prioritized, e.g., based on a charging model, userpreferences, and/or predetermined agreements. Different applications,e.g., push-to-talk feature, voice phone call, video stream, still videoimage, text data, etc., may have different transmission latencyrequirements. Relative importance levels between competing portions ofuplink data may change as new uplink user data/info is received, e.g.,via user I/O devices 308. The importance level associated to a portionof uplink data may change as a function of time. For example, a portionof data may represent information for a voice over Internet Protocol(VoIP) call, which has certain latency constraints; therefore as timeadvance, without transmission of the buffered VoIP data and theacceptable window for transmission begins to shorten, the importancelevel may increase.

Wireless terminal identification information 344 includes, e.g., a WT IPaddress and a BS 200 assigned WT active user identifier. Base stationidentifier information 346 includes an identifier, e.g., a valuedistinguishing the specific BS 200 point of network attachment to whichWT 300 is using as its current point of network attachment, from among aplurality of different BS point of network attachment in the wirelesscommunications system. In some embodiments BS ID information 346includes information identifying a specific sector and/or carrierfrequency being used by the BS point of network attachment.Device/session/resource information 348 includes uplink and downlinksegments, e.g., traffic channel segments, assigned to WT 300 and sessioninformation including address and routing information pertaining to peernodes of WT 300 in communication sessions with WT 300. Channel qualityinformation 350 includes information measured, derived and estimatedpertaining to the wireless communications channel between WT 300 and BS200. Channel quality information 350 includes detected changeinformation 352 identifying changes in the channel quality and detectedchanges which can be expected to result in changes in channel quality.

Estimated power information 354 is an output of the power monitor module326 and includes back-off power information and/or informationpertaining to the battery condition and current state of battery drain.Amount of uplink transmit data 356 is a measure of the amount of userdata waiting to be transmitted on uplink traffic channel segments to BS200. Amount of uplink transmit data 356 includes, e.g., informationidentifying amounts of data which: have not yet been transmitted, havebeen transmitted or are in the process of transmission but the WT doesnot know success/failure status of the transmission and amounts of datawhich have been unsuccessfully transmitted and require retransmission.Amount of uplink transmit data 356 varies as new data to transmit isreceived via user I/O interfaces 308, as data is successfullytransmitted, and as buffered data to be transmitted is dropped, e.g.,due to a timing requirement associated with the data being exceeded.Received maximum allowed uplink data rate 358 includes informationidentifying the BS assigned maximum uplink data rate indicatorindicating the maximum uplink data rate that the WT 300 is permitted touse for assigned uplink traffic channel segments to which the rateindicator corresponds. Different assigned uplink traffic channelsegments may be assigned different maximum uplink data rates.

Uplink assigned segment information 360 includes information identifyingthe uplink traffic channel segments assigned by BS 200 to WT 300, e.g.,in received uplink segment assignment messages 392. Uplink assignedsegment info 360 also includes information to be communicated via thoseassigned segments, e.g., user data 398 and data rate information 399 inuplink traffic channel messages 396. Selected uplink transmission rate362 includes the selection by module 332 for each assigned uplinktraffic channel segment, the selected data rate being less than or equalto the received maximum allowed uplink data rate 358 for the uplinktraffic channel segment.

System data/information 364 includes base station identificationinformation 365, uplink/downlink timing and frequency structureinformation 366, maximum base station allowed uplink data rateinformation 368 and uplink data rate used information 376.Uplink/downlink timing and frequency structure information 366 includes,e.g., symbol timing information, tone spacing information, number ofuplink tones, number of downlink tones, uplink carrier frequency,downlink carrier frequency, uplink bandwidth, downlink bandwidth, uplinkset of tones, downlink set of tones, uplink tone hopping information,uplink dwell information, downlink tone hopping information, downlinktraffic segment structure information, uplink traffic segment structureinformation, repetitive timing structures, e.g., symbol time intervalsand grouping of symbol time intervals into, e.g., dwells, half-slots,slots, superslots, beacon slots, ultra slots, etc. Different sets ofUL/DL timing and frequency structure information 366 may exist and bestored in WT 300 corresponding to different BSs 200 in the wirelesscommunications system.

Maximum BS allowed uplink data rate information 368 includes a pluralityof sets of data rate information (rate 1 info 370, rate M information372) and data rate determining information 374. Each set of rate info(370, 372) corresponding to one of the potential data rates that may bedetermined by module 330 to be indicated as a maximum uplink datatransmission rate, e.g., for an assigned uplink traffic channel segment.Data rate determining information 374 includes information used todecode a received signal including max uplink data rate indicatorinformation and to extract the data rate level being communicated fromthe base station.

Uplink data rate used information 376 includes a plurality of sets ofdata rate information (rate 1 information 378, rate N information 380),data rate selection criteria 382, and encoding information 384. Each setof data rate information (378, 380) corresponds to a possible uplinkdata rate which can be used by WT 300 for transmission of uplink trafficchannel segment signals. Each uplink data rate corresponds to codingrate and/or modulation type information. Data rate selection criteria382 includes predetermined and/or dynamic values, limits, comparisonreferences, etc., used by UL data rate selection module 332 whenchoosing a selected UL data transmit rate 362 from the set of data ratesin information (378, 382) for a given uplink traffic channel segment,the selected data rate 362 being less than or equal to the maximumallowed uplink data rate for the given uplink traffic channel segment.Encoding information 384 includes information used to encode a selecteduplink data transmit rate 362 with the user data for an uplink trafficchannel segment. For example, for a given uplink traffic channel segmentwithin the uplink timing structure used by the BS 200, the encodinginformation 384 may specify a set of locations, e.g., tone and symboltiming positions within a time frequency grid, for which uplink signalscommunicated using those locations have additional energy added inaddition to the normal energy level used to communicate the userdata/information. Different patterns of sets of locations for a givenuplink traffic channel segment may correspond to different uplink datarates used.

In some embodiments, different sets of information 366, 368 and/or 376may exist for different base stations within the wireless communicationssystem. For a given base station for a given uplink traffic channelsegment within the uplink structure, the number M of max BS alloweduplink data rates (370, 372) is less than or equal to the number N ofuplink data rates used (378, 380). In some embodiments, the number ofmax BS allowed uplink data rates M (370, 372) is less than the number Nof uplink data rates used (378, 380). In some such embodiments, themaximum uplink data rate indicator includes, at most, a number of bitswhich is less than the number of bits required to uniquely identify theplurality of possible uplink data transmission rates.

FIG. 4 is a drawing 400 illustrating exemplary base station maximumuplink data rate indicator levels 402 and exemplary corresponding uplinkdata rate levels 404 that may be selected and used by a wirelessterminal, e.g., for a set of uplink signals. In the example of FIG. 4,there are three potential base station indicated maximum data rateindicator levels (level 0, level 2, and level 6), while there are 7potential rate levels that are supported by the wireless terminal foruplink transmissions (level 0, level 1, level 2, level 3, level 4, level5, and level 6). Rate level 0 identifies the lowest data rate while ratelevel 6 identifies the highest data rate.

Consider that the base station decides that the maximum data rateindicator should indicate rate level 0. The base station sends a datarate indicator included in a downlink message to the wireless terminal.The wireless terminal receives the data rate indicator and determinesthat it may only use rate 0 for uplink transmissions. This scenario isrepresented by arrow 406.

Now consider that the base station decides that the maximum data rateindicator should indicate rate level 2. The base station sends a datarate indicator included in a downlink message to the wireless terminal.The wireless terminal receives the data rate indicator and determinesthat it may use either rate 0, 1 or 2 for uplink transmissions. Thisscenario is represented by arrows 408.

Now consider that the base station decides that the maximum data rateindicator should indicate rate level 6. The base station sends a datarate indicator included in a downlink message to the wireless terminal.The wireless terminal receives the data rate indicator and determinesthat it may use either rate 0, 1, 2, 3, 4, 5, 6 for uplinktransmissions. This scenario is represented by arrows 410.

In this exemplary embodiment, the number of possible BS indicatedmaximum data rate indicator levels, 3, can be represented using two bitswhile the number of possible data rate levels supported by the wirelessterminal, 7, can be represented using 3 bits.

In some embodiments, the number of BS maximum data rate indicated levelsis chosen to be a value=2^(A), where A is a positive integer and wherethe number of data rate levels supported by the WT is chosen to avalue=2^(B), where B is also an integer, and where 2^(A)≦2^(B). In otherembodiments, the number of BS max data rate indicated levels 2^(A) isless than the number of data rate levels supported by the WT 2^(B), insuch a case A<B.

FIG. 5 illustrates features of the present invention used to convey awireless terminal's selection of uplink data rate used concurrently withthe data/information to be communicated in the uplink signaling. Inother embodiments the uplink data rate being used is communicatedseparately from the transmitted data or the uplink data rate being usedis determined by the base station without the rate being explicitlycommunicated to the base station. In accordance with one feature of thepresent invention, in at least one exemplary embodiment additionalenergy is placed on some of the uplink signals, the location of theadditional energy is used to determine the data rate used from among aplurality of possible data rates. Drawings 500 and 550 of FIG. 5 areplots for an exemplary uplink tone of energy level on vertical axis 502vs time, expressed in OFDM symbol index within a dwell, on horizontalaxis 504. In this example, a dwell 506 includes seven successive OFDMsymbol time intervals, and uplink tones are assigned to a wirelessterminal on a per dwell basis and not frequency hopped during the dwell.The nominal energy level for a signal is represented as level 508, whilethe higher than normal energy level is represented by energy level 510.The difference between energy levels 512 is shown to be a delta of 2 dB.In some embodiments, the power difference is higher. In someembodiments, the power difference is the same in terms of dB for eachdata rate level, but has been determined based on satisfyingrequirements of the lowest data rate level. In still other embodiments,the power difference is a function of the data rate level.

Table 580 identifies position within the dwell of the higher energy tonesignal, first column 582, while second column 584 identifies thecorresponding data rate level being used by the WT for the dwell for theexemplary tone. Drawing 500, in which the higher energy has been placedon the signal for position 1 514 within the dwell 506 signifies thatdata rate 0, the lowest data rate, is being used for the uplink signalconveyed. Drawing 550, in which the higher energy has been placed on thesignal for position 2 552 within the dwell 506 signifies that data rate1 is being used for the uplink signal conveyed.

FIG. 6 is a drawing 600 illustrating exemplary uplink traffic channelsegments in a wireless communications system. In the example of FIG. 6,the uplink timing structure divides the uplink air link resource usedfor uplink traffic channels segments into 76 distinct segments a subsetof which is shown in FIG. 6, with the 76 segments repeating over time.Exemplary uplink traffic channel segments 0-14 and 17 are shown as wellas portions of segments 15-16, 18-19, 71, 73-74, and 76. Each of the 76segments includes one or more tones, of 77 possible tones, for one ormore symbol transmission time periods. Logical uplink tones (0 . . . 76)are indicated on vertical axis 602 while dwell index (0 . . . 27) inuplink timing structure is indicated on horizontal axis 604. Eachlogical tone corresponds to an actual physical tone. The relationshipbetween the logical and physical tones can be fixed, e.g., with eachlogical tone corresponding to the same physical tone over time, or canvary, e.g., according to a predetermined tone hopping sequence used toassign physical tones to logical tones. Different segments within theuplink timing structure have different shapes, e.g., more tones for ashorter duration, such as uplink traffic channel segment 0, or fewertones for a longer duration, such as uplink traffic channel segment 5.

A base station's scheduler assigns uplink traffic channel segments toWTs. The base station decides which segments and how many are assignedto a wireless terminal. The logical tones within the segment for theduration of the segment are assigned to a wireless terminal; however, insome embodiments, due to tone hopping on dwell boundaries, the physicaltones used by the wireless terminal may change from dwell to dwellwithin the segment. A dwell may include a fixed number of symboltransmission time periods during which the mapping between physical andlogical tones remains fixed. In many wireless communications systems,the data/information for each uplink traffic channel segment istypically coded at a coding rate which is used throughout the segment,and the modulation scheme used for the segment is the same. Therefore,uplink data rate information can be communicated on a per uplink trafficchannel segment basis.

In accordance with the present invention, the base station selects andcommunicates maximum uplink data rate indicators, each maximum uplinkdata rate indicator indicating the maximum uplink data rate that may beused by the wireless terminal for an assigned uplink segment orsegments. The wireless terminal receives the maximum uplink data rateindicator and selects, using its own criteria and current information,which uplink data rate to utilize for the uplink traffic channelsegment, the WT selected uplink utilized data rate, said WT selecteduplink data rate being less or equal to the maximum uplink data rateindicated by the BS maximum uplink data rate indicator. The WT selecteduplink data rate corresponds to a coding rate and/or modulation scheme.

FIG. 7 is a table 700 illustrating exemplary data rate options availableto a wireless terminal for an uplink traffic segment. First row 702describes the information included in each column of the table. Firstcolumn 712 lists the available data rate options (0, 1, 2, 3). Secondrow 704 includes data rate 0 option information; third row 706 includesdata rate 1 option information; fourth row 708 includes data rate 2option information; fifth row 710 includes data rate 3 optioninformation. Second column 714 lists the number of frames (1, 2, 3, 5).Third column 716 lists the number of information bits (224, 432, 640,1056). Fourth column 718 lists the codeword length 1344. Sixth column720 lists the approximate coding rate (1/6, 1/3, 1/2, 5/6). Seventhcolumn 722 lists the modulation constellation used (QPSK, QPSK, QPSK,QPSK). Eighth column 724 lists the per tone relative transmission poweroffset value (0 dB, 73/32 dB, 129/32 dB, 247/32 dB).

It may be observed, that in the example of FIG. 7, as the data rate usedincreases, the power utilized by the wireless terminal increases andthus the level of interference created by the WT with respect to otherWTs, e.g., in adjacent cells and/or sectors using the same set of tones,in the system also increases. The base station may control overallsystem interference levels by indicating a maximum indicated data ratelevel to the wireless terminal, thus restricting the WTs choice ofuplink rate options. The wireless terminal may decide to conserve itsbattery resources by selecting a data rate lower than the allowedmaximum value permitted by the base station.

FIG. 8 is a drawing 800 illustrating an exemplary uplink trafficsegment, and the concentration of additional energy on a subset ontone-symbols within the dwell to convey the uplink data rate used forthe segment, in accordance with the present invention. FIG. 8 plotslogical tone index in exemplary uplink traffic channel segment 0 on thevertical axis 802 vs time (OFDM symbol index within the segment) onhorizontal axis 804. The exemplary segment is further divided into fourdwells (dwell 1 806, dwell 2 808, dwell 3 810, dwell 4 812), each dwellincluding 7 successive OFDM symbol time intervals. The exemplary uplinktraffic segment illustrated by grid 800 may represent traffic segment 0of FIG. 6. In some embodiments, uplink traffic channel segments includea different number of dwells, e.g., 8 or 16 dwells instead of fourdwells per segment. In such embodiments, methods described with respectto the four dwell segment embodiment can be extended to those otherembodiments. The basic unit of the segment is a tone-symbol representedby a small square, each tone-symbol occupying one tone for a duration ofone OFDM symbol time interval. A modulation symbol may be conveyed oneach tone-symbol of the segment.

In accordance with the present invention, a pattern of locations whereadditional energy is concentrated on a subset of signals within thesegment identifies the uplink data rate used by the WT for transmissionof the uplink traffic channel segment. Different data rates, e.g., asshown in FIG. 7 may be used by the WT. In the exemplary embodiment ofFIG. 8, the first OFDM symbol time interval of each dwell is used toconvey one tone which has an additional energy concentration, e.g.,representing a power difference over the signals communicated on theother tones.

Legend 814 indicates that tone-symbols of type 816 represented withcrosshatch shading are part of a pattern corresponding to WT selecteddata rate 0, while tone-symbols of type 818 represented with horizontalline shading correspond to WT selected data rate 2.

FIG. 8 illustrates two exemplary cases of different WT uplink selecteddata rates on the same grid 800. Consider that the WT has selected touse data rate 0, then additional energy is placed on the signalscorresponding to tone symbols: (tone0, OFDM symbol index 1), (tone 7,OFDM symbol index 8), (tone 14, OFDM symbol index 15), (tone 21, OFDMsymbol index 22), while the other tone-symbols of the segment conveysignals with nominal energy levels. Now consider that the WT hasselected to use data rate 2, then additional energy is placed on thesignals corresponding to tone symbols: (tone 2, OFDM symbol index 1),(tone 9, OFDM symbol index 8), (tone 16, OFDM symbol index 15), (tone23, OFDM symbol index 22), while the other tone-symbols of the segmentconvey signals with nominal energy levels. Other exemplary data rates,e.g., data rate 1 and data rate 3 may be indicated by differentpatterns. In some embodiments, each of the patterns represents the sameslope within the grid, but with a different offset. In some embodiments,the different patterns may be represented by different slopes and/orincluding different offsets within the grid.

By selecting a tone-symbol with the same symbol timing position withineach dwell, e.g., the first position within each dwell, for theplacement of additional energy, the energy used for each OFDM symboltime interval within the each dwell of the uplink segment does notchange as a function of the data rate used, as would be the case if theapproach of FIG. 5 was used, where position within the dwell determinesrate used.

In the example of FIG. 8, the wireless terminal can expect toconcentrate a small amount of additional energy on one tone during eachfirst OFDM symbol time interval of each dwell for each uplink trafficchannel segment. During the remaining OFDM symbol time intervals of thedwell, the energy levels are nominal.

In addition, the base station knows that the additional energy will beconcentrated on one of the tones of each first OFDM symbol index of eachdwell of the uplink traffic channel segment. This simplifies the basestation's recovery of the uplink transmitted data rate utilized by thewireless terminal and encoded in the uplink traffic segment signals.

It may be observed that the codeword length of the example of FIG. 7 is1344 bits which using QPSK, conveys 2 coded bits per modulation symbol,corresponding to 672 modulation symbols. The exemplary segment of FIG. 8includes 784 tone-symbols which can convey 784 modulation symbols. Insome embodiments, some tone-symbols of the segment are reserved forreference modulation symbols to support reference based modulation. Forexample, one tone-symbol, e.g., the fourth OFDM tone-symbol for eachtone of the segment for each dwell can be reserved for a referencemodulation symbol, e.g., conveying the complex value (1,1). The othersix tone-symbols for each tone for each dwell of the segment can be usedto convey block encoded information bits according to the rate selectedconveyed by the pattern of additional energy within the segment, therate corresponding to a coding rate and/or a modulation scheme.

FIG. 16 is a drawing 1600 illustrating an exemplary uplink trafficsegment including tone-symbols used to convey modulation symbolsconveying information bits and tone-symbols used to convey referencemodulation symbols, and the concentration of additional energy on asubset on tone-symbols within the dwell to convey the uplink data rateused for the segment, in accordance with the present invention. FIG. 16plots logical tone index in exemplary uplink traffic channel segment 0on the vertical axis 1602 vs time (OFDM symbol index within the segment)on horizontal axis 1604. The exemplary segment is further divided intofour dwells (dwell 1 1606, dwell 2 1608, dwell 3 1610, dwell 4 1612),each dwell including 7 successive OFDM symbol time intervals. Theexemplary uplink traffic segment illustrated by grid 1600 may representtraffic segment 0 of FIG. 6. In some embodiments, uplink traffic channelsegments include a different number of dwells, e.g., eight dwellsinstead of four dwell per segment. In such embodiments, methodsdescribed with respect to the four dwell segment embodiment can beextended to those other embodiments. The basic unit of the segment is atone-symbol represented by a small square, each tone-symbol occupyingone tone for a duration of one OFDM symbol time interval. A modulationsymbol may be conveyed on each tone-symbol of the segment.

In accordance with the present invention, a pattern of locations whereadditional energy is concentrated on a subset of signals within thesegment identifies the uplink data rate used by the WT for transmissionof the uplink traffic channel segment. Different data rates, e.g., asshown in FIG. 7 may be used by the WT. In the exemplary embodiment ofFIG. 16, the first OFDM symbol time interval of each dwell is used toconvey one tone which has an additional energy concentration, e.g.,representing a power difference over the signals communicated on theother tones.

Legend 1614 indicates that tone-symbols of type 1616 represented withcrosshatch shading are part of a pattern of modulation symbols withadditional energy corresponding to WT selected data rate 0; informationbits are conveyed in tone-symbols of type 1616 using data rate 0, datarate 0 signifying a coding rate and/or a modulation scheme. Legend 1614also indicates modulation symbols at normal energy level conveyinginformation bits at data rate 0 are conveyed in tone-symbols of type1618 as indicated by no shading. In addition legend 1614 indicates thattone-symbols of type 1619 are used to convey reference modulationsymbols.

In the example of FIG. 16, consider that data rate 0 corresponds to datarate 0 of FIG. 7 signifying QPSK modulation scheme and a coding rate ofapproximately 1/6. Data rate 0 can be expressed as one frame per segmentor 224 information bits per segment or 224 information bits per 672modulation symbols used to convey block encoded information or 224information bits per 784 modulation symbols. In this example, 672tone-symbols comprising the combination of tone-symbols of type 1616 and1618 are used to convey the 1344 encoded bits of the codeword conveyingthe 224 information bits, with 2 encoded bits per QPSK modulation symboland one QPSK modulation symbol per tone-symbol. The remaining 112tone-symbols of the segment are of type 1619 and each conveys areference QPSK modulation symbol, e.g., conveying the complex value(1,1).

FIG. 9 is a flowchart 900 of an exemplary method of operating a basestation in accordance with the present invention. Operations start instep 902, where the base station is powered on and initialized. The basestation may operate using a predetermined frequency and timingstructure. The BS may register WTs, which may use the base station astheir point of network attachment. Operation proceeds from step 902 tosteps 904, 906, 908, 910 and 912.

In step 904, the base station monitors and receives uplink resourcerequests from WTs 914. The monitoring and reception process may beperformed on an ongoing repetitive basis. In some embodiments, WTs arepermitted specific times within the repetitive timing structure to sendrequests for uplink resources, e.g., requests for uplink traffic channelsegments.

In step 906, the base station schedules uplink traffic channel segmentsto WTs, e.g., WTs with outstanding requests. Step 906 includes the basestation being operated to assign at least some uplink traffic channelsegments to a wireless terminal to be used in communicating data to thebase station, said uplink traffic channel segments being wirelesscommunications channel segments dedicated to communicating uplinksignals to the base station. Step 906 includes sub-step 916 and 918. Insub-step 916, the base station performs estimates of the amount of datafor a wireless terminal to transmit, for each WT that has data totransmit in sub-step 916. Then in sub-step 918, the base stationschedules a number of uplink traffic channel segments to a WT, thenumber of segments being assigned being a function of the estimatedamount of estimated data from sub-step 916. Operation proceeds from step906 to step 920.

In step 920, the base station is operated to select, for each uplinktraffic channel segment, a maximum uplink data transmission rate thatthe wireless terminal should use, the maximum uplink data transmissionrate being one of a plurality of possible transmission data rates. Theselection by the base station can use information including the qualityof the wireless communication channel, interference estimates that theWT will generate to other WTs which will be caused by transmissions fromthe WT when the selected maximum uplink data transmission rate is usedby the WT, and/or received power information in selecting a maximum datauplink rate for a WT for one or more uplink traffic channel segmentswhich are being assigned by the scheduler to the WT. In step 920 amaximum uplink data rate indicator is selected to convey the maximumuplink data rate that the WT is permitted to use for said at least someuplink traffic channel segments. In some embodiments, the selectedmaximum uplink data transmission rate is one of a plurality of possibleuplink data transmission rates which can be selected by the base stationand indicated. In some but not all embodiments the number which can beindicated is fewer than the number of uplink data rates which can beselected and used by the wireless terminal for the transmission ofuplink signals. In various embodiments, the maximum uplink data rateindicator includes, at most, a maximum number of bits that is less thanthe number of bits required to uniquely specify the full set of uplinkdata transmission rates which can be selected and used by the wirelessterminal. For example, the possible number of maximum uplink datatransmission rates may be four which can be represented by two bits,while the number of uplink data rates that the wireless terminalsupports may be eight which would require three bits to uniquelyidentify each of the rates. Operation proceeds from step 920 to step922. In step 922, the base station is operated to transmit uplinktraffic channel assignment information and a maximum data rate indicator926 to each WT being assigned uplink traffic channel segments at thistime. Operation proceeds from step 922 via connecting node A 928 to step906 for additional scheduling. Scheduling may be performed in accordancewith a predetermined repetitive timing structure being used by the basestation.

In step 908, the base station is operated to monitor and receive channelquality reports 930 from WTs. Then, in step 932, the base stationestimates the amount of interference uplink transmissions of a WT willcause to other WTs if one or more different uplink data rates, e.g.,transmission data rates that can be considered for selection as themaximum uplink data transmission rate, are used by the wirelessterminal. This is done by taking into consideration the transmissionpower that the WT is likely to use to support the considered uplinktransmission rate. The transmission power can be predicted fromknowledge available at the BS regarding that power level that will beused by the WT given a particular coding rate, modulation scheme, and aset of channel conditions. The channel quality information of step 908,and interference estimate information of step 932 are used in step 920.Operations proceed from step 932 back to step 908 where additionalchannel quality reports are received. In some embodiments, channelquality reports from connected WTs are transmitted in predeterminedtimes within the base station's uplink timing structure.

In step 910, the base station is operated to monitor and receive powerindicator message 934, e.g., a WT power back-off message and/or batterypower message. Monitoring operation of step 910 continue on an ongoingbasis. In some embodiments, specific uplink control channel segments,within the uplink timing structure are reserved for the batteryindication messages. In some embodiments, battery indicator messages aretransmitted if battery power is low and the WT desires the BS torecognize that fact and reduce commanded and/or allowed WT transmissionpower levels. Power information obtained in step 910 is utilized in step920.

In step 912, the base station is operated to monitor and receive uplinktraffic channel segment data/information 936 including userdata/information and data rate information from WTs. Operation proceedsfrom step 912 to step 938. In step 938, the base station is operated todetermine uplink data transmission rate used by a WT. This may be donein a plurality of ways. In some but not all embodiments, thisdetermination is made from received signals included in the same uplinktraffic channel segment conveying the user data/information. In someembodiments, such as the one illustrated in FIG. 8, the uplink data rateinformation is indicated by the location of additional energy beyond theenergy used to communicate said data on a predetermined subset of one ormore signals, e.g., tones, used to communicate the data. The subset oftones used to communicate the uplink rate is, in some cases, the same asthat used to communicate the data. The one or more signals used tocommunicate rate information may be tones of an orthogonal frequencydivision multiplexed signal. In some embodiments, the amount ofadditional energy used to indicate the uplink rate being used is afunction of the data rate selected by the WT. The additional energyplaced on a tone may be a function of the lowest data rate that may beselected by the WT whether or not it is a function of the actualselected data rate. In one particular exemplary embodiment, where saidadditional energy is a function of the lowest data rate used, saidadditional energy is at least 2 dB above the energy used to transmit thedata at the lowest data rate. Each data rate, identifying a number ofdata/information bits conveyed per transmission unit, e.g., symbol orsegment. Thus the data rate may be expressed as data/information bitsper symbol or the number of data/information bits conveyed per segment.The data/information bits conveyed per segment can alternatively beexpressed as the number of data/information frames conveyed per segment,where there is a fixed number of data/information bits in adata/information frame. The data rate will correspond to a coding rateused and/or a modulation scheme used for the signaling since codingand/or modulation affect the number of actual information/data bits thatcan be conveyed using a given uplink unit. Operation proceeds from step938 to step 940. In step 940, the base station is operated to use thedetermined uplink data transmission rate to recover userdata/information conveyed in uplink traffic channel signals. Operationproceeds from step 940 to step 912. The base station may performmultiple operations of steps (912, 938, 940) in parallel, e.g.,corresponding to the different uplink traffic channel segments withinthe uplink timing structure.

FIG. 10 is a flowchart 1000 of an exemplary method of operating awireless terminal, e.g., a mobile node, in accordance with the presentinvention. The wireless terminal may be in a wireless communicationssystem including at least one base station which interacts with saidwireless terminal via a wireless communications channel. Operationsstart in step 1002, where the wireless terminal is powered on andinitialized. The wireless terminal may register with a base station,e.g., a base station corresponding to the wireless coverage area inwhich the WT is currently located, and use the base station as its pointof network attachment. Operation proceeds from step 1002 to steps 1004,1006, 1008, 1010 and 1012.

In step 1004, the wireless terminal is operated to monitor for andreceive user data/information 1014 for uplink signaling. The userdata/input 1014 is data/information corresponding to user input, e.g.,voice, text, video, etc., entered via user I/O devices, e.g.,microphone, keyboard, keypad, camera, etc. The monitoring of the userI/O devices for input, the reception and storage of received data/info1014 of step 1004 is performed on an ongoing basis.

In step 1006, the wireless terminal is operated to track availabletransmission power which can be used for transmission of data signals inthe wireless terminal. The tracking of available power may include,e.g., the determination of the amount of power remaining after power isdedicated for the transmission of a set of signals, e.g., controlsignals, under direction of one or more power control signals receivedfrom the base station. The power tracking can also include, in someembodiments, the measurement of the current battery energy level,battery status with respect to predetermined benchmark levels,estimation of remaining energy level and estimation of operational timeunder various conditions. The tracking of battery power may also includemeasurements and/or estimates of amounts and/or rates of energy levelchanges, e.g., decline during usage and/or increase during batterycharging. In step 1006, the wireless terminal may also determine whetherthe wireless terminal is currently operating on its own battery reservesor is operating from an external power source, e.g., a car's electricalsystem. The power tracking of step 1006 is performed on an ongoingbasis.

Operation proceeds from step 1006 to step 1018. In step 1018, thewireless terminal sends a power indicator message 1020, e.g., a back-offmessage and/or battery power message to the base station. This messageindicates the amount of power available for transmitting signals otherthan the set of signals, e.g., predetermined set of control signals, towhich power is allocated in response to the power control commandsreceived from the base station. The message can also indicate the amountof battery power remaining in the wireless terminal. In someembodiments, the power indicator message 1020 may be sent periodicallyby the WT in accordance with a repeating uplink timing structure used tocontrol the transmission of uplink signals. However, in some cases thetransmission of the signals may be discretionary and not use an uplinkslot dedicated to power reports. In some embodiments, the current basestation commanded WT transmission power level and/or maximumtransmission data rate indicator level are considered by the WT indeciding whether or not to send battery power information in indicatormessage 1020.

In step 1008, the wireless terminal is operated to track and/or updatethe amount of data/info, e.g., bits and/or frames to be transmitted onuplink traffic channels. The current value of the amount of uplinkdata/info to be transmitted will change as new data/info is received viaI/O devices, as data/info is in the process of transmission, asdata/info is successfully transmitted, as it is determined thatdata/info has been unsuccessfully transmitted requiring retransmission,and as buffered data/information to be transmitted is dropped, e.g., dueto a time validity window expiring. The tracking operation of step 1008is performed on an ongoing basis. Operation proceeds from step 1008 tostep 1022.

In step 1022, the wireless terminal checks as to whether there arecurrently frames to be transmitted on the uplink traffic channel. If itis determined that there are no frames to be transmitted, then the checkof step 1022 is again performed, e.g., at the next designated time inthe timing structure such as to allow sufficient time to generate auplink resource request message prior to the next opportunity for suchrequests in the timing structure. If it is determined that there areframes to be transmitted, then operation proceeds from step 1022 to step1024, where the WT sends a request 1026 to the BS for uplink trafficchannel resources. Then, in step 1028, the wireless terminal is operatedto monitor and receive uplink traffic channel segment assignmentinformation 1030 and a maximum uplink data rate indicator 1032, saiduplink traffic channel assignment segment information 1030 and saidmaximum uplink data rate indicator 1032 having been transmitted from thebase station. The maximum uplink data rate indicator indicates a maximumuplink data transmission rate that the wireless terminal is permitted touse for at least one uplink segment. The received uplink traffic channelassignment information 1030 indicates at least one uplink segmentassigned to said WT by said BS for using in communicating uplinksignals, said maximum uplink data rate indicator indicating the maximumuplink data transmission rate which can be used in said at least oneuplink segment assigned to said WT. In some embodiment, the maximumuplink data rate indicator includes, at most, a number of bits which isless than the number of bits required to uniquely identify the pluralityof possible uplink data transmission rates which can be selected by thewireless terminal for transmitting uplink signals. As there aregenerally a plurality of WTs competing for a limited number of uplinktraffic channel segments, the WT may not receive the requestedassignment on the next set of uplink traffic channel segmentassignments. In some embodiments, the wireless terminal, if not grantedthe request immediately waits, e.g., for a number of assignmentopportunities before resubmitting the request. In some embodiments, thewireless terminal, if not granted the request immediately, shouldresubmit the request. In some embodiments, separate messages are used bythe base station for conveying assignment information and maximum uplinkrate indicator information. In some embodiments, both uplink trafficchannel assignment information and maximum data rate indicatorinformation are in the same message. In some embodiments, the operationsof steps 1022, 1024, and/or 1028 may be performed at specific times withrespect to the timing structure used by the base station. Operationproceeds from step 1028 to step 1034 and to step 1022 via connectingnode A 1036.

In step 1034, the wireless terminal having been assigned an uplinktraffic channel segment or segments by the base station along with amaximum uplink rate indicator, selects an uplink transmission rate touse for the uplink traffic channel segment or segments. In variousembodiments, the wireless terminal performs the selection as a functionof the maximum data rate indicator, the amount of data to be transmittedto the base station, the importance of the data to be transmitted, thepower information, channel quality conditions, and/or detected changesin channel conditions. The uplink data transmission rate to use,selected by the WT in step 1034 is a value less than or equal to thedata rate indicated by the received maximum uplink data rate indicator.Operation proceeds from step 1034 to step 1038.

In step 1038, which is performed in embodiments where the WT expresslysignals the selected uplink data rate to the base station, the wirelessterminal is operated to encode the selected uplink data transmissionrate, for example, with the data/info to be transmitted in the uplinktraffic channel segment. In some embodiments, the WT selected andutilized uplink data rate is indicated by placing additional energybeyond the energy used to communicate the data on a predetermined subsetof signals used to communicate the data, the subset corresponding to theuplink data rate used to communicate the data. In some embodiments, saidadditional energy is a function of the uplink data rate selected by thewireless terminal. In some embodiments, said additional energy is afunction of the lowest data rate. In some embodiments, the additionalenergy is at least 2 dB above the energy used to transmit the data.Operation proceeds from step 1038 to step 1040. The data rate may becommunicated in some embodiments using a signal which is sent separatelyfrom the data/information to be communicated using the selected uplinkdata rate.

In step 1040, the wireless terminal is operated to transmit the uplinktraffic channel segment signals 1042 including user data/info and theselected uplink data transmission rate, e.g., at the designated timewith respect the uplink traffic segment position within the repetitivetiming structure. An Ack/Nak corresponding to the transmitted signals ofstep 1042 is used by the tracking operations of step 1008 to update theamount of data to be transmitted.

In step 1010, the wireless terminal is operated to determine and/orupdate the importance of data/info to be transmitted on uplink trafficchannel segments. For example, different portions of uplink user data tobe transmitted may have different levels of importance, e.g., in termsof priority, application, urgency to transmit, etc. Differentapplications and/or peers may be prioritized, e.g., based on a chargingmodel, user preferences, and/or predetermined agreements. Differentapplications, e.g., push-to-talk feature, voice phone call, videostream, still video image, text data, etc., may have differenttransmission latency requirements. Relative importance levels betweencompeting portions of uplink data may change as new uplink userdata/info is received. The importance level associated to a portion ofuplink data may change as a function of time. For example, a portion ofdata may represent information for a voice over Internet Protocol (VoIP)call, which has certain latency constraints; therefore as time advances,without transmission of the buffered VoIP data and the acceptable windowfor transmission begins to shorten, the importance level for thatportion of data may increase. The operations of step 1010 are performedon an ongoing basis. The determinations of step 1010 are used by the WTin deciding which portions of the data to transmit first and selectingthe uplink data transmission rate used in step 1034.

In step 1012, the wireless terminal is operated to monitor and determinechannel quality conditions of the communications channel between thebase station and wireless terminal. Step 1012 includes sub-step 1044 and1046. In sub-step 1044, the wireless terminal is operated to monitor anddetect changes in channel conditions. In step 1046, the wirelessterminal is operated to generate and transmit channel quality reports1048 to the base station. In general, the channel condition changeinformation is updated on a more frequent basis and includes moreinformation than the channel quality feedback reports to the basestation, providing the wireless terminal with current and pertinentinformation to use in the uplink data rate selection step 1034.

FIG. 11 is another example of exemplary data rate options available toan exemplary wireless terminal for an uplink traffic segment, andexamples of corresponding maximum uplink data rate indicators, inaccordance with the present invention. FIG. 11 includes a table 1100illustrating exemplary data rate options available to a wirelessterminal for an uplink traffic segment. Table 1100 illustrates the WTuplink data rate is, in some embodiments, a function of both the codingrate used and the modulation scheme used. First row 1102 describes theinformation included in each column of the table. First column 1120lists the available data rate options (0, 1, 2, 3, 4, 5, 6, 7). Secondrow 1104 includes data rate 0 option information; third row 1106includes data rate 1 option information; fourth row 1108 includes datarate 2 option information; fifth row 1110 includes data rate 3 optioninformation; sixth row 1112 includes data rate 4 option information,seventh row 1114 includes data rate 5 option information; eighth row1116 includes data rate 6 option information; ninth row 1118 includesdata rate 7 option information. Second column 1124 lists the number offrames (1, 2, 3, 4, 5, 6, 8, 10). Third column 1126 lists the number ofinformation bits (224, 432, 640, 848, 1056, 1264, 1680, 2096). Fourthcolumn 1128 lists the codeword length (1344, 1344, 1344, 1344, 2688,2688, 2688, 2688). Sixth column 1130 lists the approximate coding rate(1/6, 1/3, 1/2, 2/3, 5/12, 1/2, 2/3, 3/4). Seventh column 1132 lists themodulation constellation used (QPSK, QPSK, QPSK; QPSK, QAM16, QAM16,QAM16, QAM16).

FIG. 11 also includes a table 1140 of a first example of a correspondingmaximum uplink data rate indicator that may be selected by a basestation and transmitted to a wireless terminal supporting the exemplaryuplink data rate options for uplink traffic segments of table 1100.First row 1142 describes the information listed in each column of thetable. Second row 1144, lists information corresponding to a maximumuplink data rate indicator value of 0; third row 1146 lists informationcorresponding to a maximum uplink data rate indicator value of 1; fourthrow 1148 lists information corresponding to a maximum uplink data rateindicator value of 2; fifth row 1150 lists information corresponding toa maximum uplink data rate indicator value of 3. Second column 1154lists the (MSB, LSB) used to represent each of the four possible datarate indicator values (0, 1, 2, 3) as ((0,0), (0,1), (1,0), (1,1)),respectively. Third column 1156 lists the maximum wireless terminal datarate level permitted corresponding to each of the four possible datarate indicator values (0, 1, 2, 3) as (WT data rate option 0, WT datarate option 3, WT data rate option 5, WT data rate option 7),respectively. Fourth column 1156 lists the WT data rates permitted foreach of the four possible data rate indicator values (0, 1, 2, 3) as (WTdata rate 0, WT data rate 0-3, WT data rate 0-5, WT data rate 0-7),respectively. It should be noted that in this exemplary embodiment. theWT supports 8 different uplink data rates which could be represented by3 bits, while the maximum uplink data rate indicator includes only fourvalues which can be represented by 2 bits.

FIG. 11 also includes a table 1160 of a second example of acorresponding maximum uplink data rate indicator that may be selected bya base station and transmitted to a wireless terminal supporting theexemplary uplink data rate options for uplink traffic segments of table1100. First row 1162 describes the information listed in each column ofthe table. Second row 1164, lists information corresponding to a maximumuplink data rate indicator value of 0; third row 1166 lists informationcorresponding to a maximum uplink data rate indicator value of 1; fourthrow 1168 lists information corresponding to a maximum uplink data rateindicator value of 2; fifth row 1170 lists information corresponding toa maximum uplink data rate indicator value of 3. Second column 1174lists the (MSB, LSB) used to represent each of the four possible datarate indicator values (0, 1, 2, 3) as ((0,0), (0,1), (1,0), (1,1)),respectively. Third column 1176 lists the maximum wireless terminal datarate permitted corresponding to each of the four possible data rateindicator values (0, 1, 2, 3) as (WT data rate option 0, WT data rateoption 3, WT data rate option 5, WT data rate option 7), respectively.Fourth column 1178 lists the WT data rates permitted for each of thefour possible data rate indicator values (0, 1, 2, 3) as (WT data rate0, WT data rate 0-3, WT data rate 4-5, WT data rate 4-7), respectively.In this embodiment, for each maximum uplink data rate indicator value,the wireless terminal can select from a predefined subset of WT datarates corresponding to that data rate indicator values, the WT datarates within the subset being data rates that are less than or equal tothe maximum uplink data rate indicator value. Although in this exampleeach subset of data rates is shown as a continuous block of data rates,in general, the WT uplink data rates included in each subset ofpredefined data rates need not be continuous.

FIG. 12 is another example of exemplary data rate options available toan exemplary wireless terminal for an uplink traffic segment, andexamples of corresponding maximum uplink data rate indicators, inaccordance with the present invention. FIG. 12 includes a table 1200illustrating exemplary data rate options available to a wirelessterminal for an uplink traffic segment. First row 1202 describes theinformation included in each column of the table. First column 1220lists the available data rate options (0, 1, 2, 3, 4, 5, 6, 7). Secondrow 1204 includes data rate 0 option information; third row 1206includes data rate 1 option information; fourth row 1208 includes datarate 2 option information; fifth row 1210 includes data rate 3 optioninformation; sixth row 1212 includes data rate 4 option information,seventh row 1214 includes data rate option 5 information; eighth row1216 includes data rate 6 option information; ninth row 1218 includesdata rate 7 option information. Second column 1224 lists the number offrames (1, 2, 3, 4, 5, 6, 8, 10). Third column 1226 lists the number ofinformation bits (120, 224, 328, 432, 536, 640, 848, 1056). Fourthcolumn 1228 lists the codeword length (672, 672, 1344, 1344, 1344, 1344,1344, 1344). Sixth column 1230 lists the approximate coding rate (3/17,1/3, 1/4, 1/3, 2/5, 1/2, 2/3, 5/6). Seventh column 1232 lists themodulation constellation used (BPSK, BPSK, QPSK, QPSK, QPSK, QPSK, QPSK,QPSK). Eighth column 1234 lists the per tone relative transmission poweroffset value (P0, P1, P2, P3, P4, P5, P6, P7). In some embodiments, thepower levels are such that P0<P1<P2<P3<P4<P5<P6<P7.

FIG. 12 also includes a table 1240 of a first example of a correspondingmaximum uplink data rate indicator that may be selected by a basestation and transmitted to a wireless terminal supporting the exemplaryuplink data rate options for uplink traffic segments of table 1200.First row 1242 describes the information listed in each column of thetable. Second row 1244, lists information corresponding to a maximumuplink data rate indicator value of 0; third row 1246 lists informationcorresponding to a maximum uplink data rate indicator value of 1; fourthrow 1248 lists information corresponding to a maximum uplink data rateindicator value of 2; fifth row 1250 lists information corresponding toa maximum uplink data rate indicator value of 3. Second column 1254lists the (MSB, LSB) used to represent each of the four possible datarate indicator values (0, 1, 2, 3) as ((0,0), (0,1), (1,0), (1,1)),respectively. Third column 1256 lists the maximum wireless terminal datarates permitted corresponding to each of the four possible data rateindicator values (0, 1, 2, 3) as (WT data rate option 0, WT data rateoption 1, WT data rate option 4, WT data rate option 7), respectively.Fourth column 1258 lists the WT data rates permitted for each of thefour possible data rate indicator values (0, 1, 2, 3) as (WT data rate0, WT data rate 0-1, WT data rate 0-4, WT data rate 0-7), respectively.It should be noted that in this exemplary embodiment, the WT supports 8different uplink data rates which could be represented by 3 bits, whilethe maximum uplink data rate indicator supports a maximum of fourpossible values which can be represented by 2 bits.

FIG. 12 also includes a table 1260 of a second example of acorresponding maximum uplink data rate indicator that may be selected bya base station and transmitted to a wireless terminal supporting theexemplary uplink data rate options for uplink traffic segments of table1200. First row 1262 describes the information listed in each column ofthe table. Second row 1264, lists information corresponding to a maximumuplink data rate indicator value of 0; third row 1266 lists informationcorresponding to a maximum uplink data rate indicator value of 1; fourthrow 1268 lists information corresponding to a maximum uplink data rateindicator value of 2; fifth row 1270 lists information corresponding toa maximum uplink data rate indicator value of 3. Second column 1274lists the (MSB, LSB) used to represent each of the four possible datarate indicator values (0, 1, 2, 3) as ((0,0), (0,1), (1,0), (1,1)),respectively. Third column 1276 lists the maximum wireless terminal datarate permitted corresponding to each of the four possible data rateindicator values (0, 1, 2, 3) as (WT data rate option 0, WT data rateoption 1, WT data rate option 4, WT data rate option 7), respectively.Fourth column 1278 lists the WT data rates permitted for each of thefour possible data rate indicator values (0, 1, 2, 3) as (WT data rate0, WT data rate 0-1, WT data rate 2-4, WT data rate 2-7), respectively.In this embodiment, for each maximum uplink data rate indicator value,the wireless terminal can select from a predefined subset of WT datarates corresponding to that rate indicator values, the WT rates withinthe subset being rates that are less than or equal to the maximum uplinkdata rate indicator value. Although in this example each subset of datarates is shown as a continuous block of data rates, in general, the WTuplink data rates included in each subset of predefined data rates neednot be continuous.

FIG. 13 is a table 1300 illustrating another set of exemplary data rateoptions available to a wireless terminal for an uplink traffic segment.First row 1302 describes the information included in each column of thetable. First column 1312 lists the available data rate options (0, 1, 2,3). Second row 1304 includes data rate 0 option information; third row1306 includes data rate 1 option information; fourth row 1308 includesdata rate 2 option information; fifth row 1310 includes data rate 3option information. Second column 1314 lists the number of frames (1, 2,3, 5). Third column 1316 lists the number of information bits (224, 432,640, 1056). Fourth column 1318 lists the codeword length 1344. Sixthcolumn 1320 lists the approximate coding rate (1/6, 1/3, 1/2, 5/6).Seventh column 1322 lists the modulation constellation used (QPSK, QPSK,QPSK, QPSK). Eighth column 1324 lists the per tone relative transmissionpower offset value (0 dB, 0 dB, 0 dB, 0 dB).

It may be observed, that in the example of FIG. 13, that the WT powerused remains constant event though the data rate changes. Thus thewireless terminal by selecting a lower data rate to use than the maximumpermitted uplink data rate as communicated by the received uplinkmaximum data rate indicator value, can improve the probability that thetransmitted uplink signals for the uplink traffic channel segment willbe successfully received by the base station and thus improves uplinksignaling reliability. The base station may control overall systeminterference levels by indicating a maximum indicated data rate level tothe wireless terminal, thus restricting the WTs choice of user selectionoptions. The wireless terminal may decide, e.g., based on informationavailable to the WT at a given time such as importance, e.g., urgency,of a portion of data to be communicated, that a higher probability oftransmission success is more advantageous to the WT than a higher datarate and thus the WT may select a lower data rate.

In various embodiments, for the same WT, some WT uplink data rateoptions may have the same associated power levels and some WT uplinkdata rate options may have different associated power levels.

FIG. 14 illustrates an alternative approach, with respect to thepreviously presented approach of placing additional energy on a subsetof signals, to conveying WT selected uplink data rate in an uplinktraffic segment. FIG. 14 is a drawing 1400 illustrating an exemplaryuplink traffic segment, and the partitioning of the segment into asubset of tone-symbols to convey the uplink data rate used for the userdata/info signals of the segment and a subset of tone-symbols used toconvey user data/information, in accordance with some embodiments thepresent invention. FIG. 14 plots logical tone index in exemplary uplinktraffic channel segment 0 on the vertical axis 1402 vs time (OFDM symbolindex within the segment) on horizontal axis 1404. The exemplary segmentis further divided into four dwells (dwell 1 1406, dwell 2 1408, dwell 31410, dwell 4 1412), each dwell including 7 successive OFDM symbol timeintervals. The exemplary uplink traffic segment illustrated by grid 1400may represent traffic segment 0 of FIG. 6. The basic unit of the segmentis a tone-symbol represented by a small square, each tone-symboloccupying one tone for a duration of one OFDM symbol time interval. Amodulation symbol may be conveyed on each tone-symbols of the segment.

In accordance with some embodiments of present invention, apredetermined subset of locations within the segment is dedicated toconveying the uplink data rate used within the segment for userdata/information of the segment. Different data rates, e.g., 8 differentuplink data rates which may be represented by 3 information bits, may beused by the WT. Each uplink data rate may signify a coding rate andmodulation scheme, e.g., BPSK, QPSK, and/or QAM16, used for userdata/information modulation symbols of the uplink traffic channelsegment. In the exemplary embodiment of FIG. 14, six tone-symbols of thesegment have been reserved to convey the three data rate usedinformation bits. A non-coherent modulation scheme may be used to conveythose three information bits over six modulations symbols correspondingto the six reserved tone-symbol locations of the uplink traffic channelsegment.

Legend 1414 indicates that the 6 tone-symbol of type 1416 in grid 1400represented with crosshatch shading are part of a subset of tone-symbolsused to convey the WT selected uplink data rate, while the 778tone-symbols of type 1418 represented with no shading in grid 1400 areused to convey WT uplink user data/information. In some embodiments, themodulation scheme used for the tone-symbols of type 1416 is the sameirrespective of the modulation scheme used for the user data/informationtone-symbols of type 1418. In such an embodiment, the WT would select anuplink data rate as a function of the received maximum uplink data rateindicator and other WT selection criteria, e.g., amount of data,importance of data, changes in quality, channel conditions, poweravailable for transmitting user data, battery power status, etc. Theselection of uplink data rate would identify a data rate level, the datarate level having a corresponding coding rate and modulation scheme. Thedata rate level would be encoded into a set of modulation symbols forthe six tone-symbol locations of type 1416 using a predeterminednon-coherent modulation scheme which does not change. The userdata/information would be encoded and modulated using the selectedcorresponding coding rate and modulation scheme onto a set of modulationsymbols for the 778 tone-symbols of type 1418. The base station wouldreceive the modulation symbols conveyed by the tone-symbols of theuplink traffic channel segment, demodulate and decode the rate signalsconveyed in the six tone-symbols of type 1416, thus obtaining the datarate option used for the user data/information. Having determined thedata rate option used, the base station determines, e.g., via a look-uptable, the modulation scheme and coding rate used for the userdata/information modulation symbols conveyed on tone-symbols of type1418, demodulates and decodes the user data/information received signalsof the segment recovering the user data/information bits.

FIG. 15 includes table 1500 illustrating that in some embodiments, thewireless terminal selected uplink data transmission rate may becommunicated by a power difference placed on a subset of symbols of theuplink segment and the power difference may be a fixed value in terms ofdB above the power level used to communicate the user data/informationmodulation symbol regardless of the uplink data rate selected. Thesubset of symbols being located within the segment to define a pattern,different patterns defining different data rates. Table 1500 includes afirst column 1502 listing eight exemplary uplink data rate options (rate0, rate 1, rate 2, rate 3, rate 4, rate 5, rate 6, rate 7), where rate 0corresponds to the lowest rate and rate 7 corresponds to the highestrate. Second column 1504, lists the power difference on the subset ofmodulation symbols used to convey the selected uplink data rate via apattern within the segment. Each value of column 1504 is the same C1 dB,where C1 is a constant, e.g., 2 dB. C1 may be selected to allow theselected data rate to be recovered under a specified worst casecondition, which in some embodiments, is the lowest rate, e.g., datarate option 0, using the lowest transmission power level.

FIG. 15 also includes table 1506 illustrating that in some embodiments,the wireless terminal selected uplink data transmission rate may becommunicated by a power difference placed on a subset of symbols of theuplink segment and the power difference may be an amount X dB above thepower level used to communicate the user data/information modulationsymbol where X is a function of the uplink data rate selected. Thewireless terminal and base station would both know the power differencerelationship being employed in the system. The subset of symbols beinglocated within the segment to define a pattern, different patternsdefining different data rates. Table 1506 includes a first column 1508listing eight exemplary uplink data rate options (rate 0, rate 1, rate2, rate 3, rate 4, rate 5, rate 6, rate 7), where rate 0 corresponds tothe lowest rate and rate 7 corresponds to the highest rate. Secondcolumn 1510, lists the power difference on the subset of modulationsymbols used to convey the selected uplink rate via a pattern within thesegment. For each data rate (0, 1, 2, 3, 4, 5, 6, 7), the powerdifference X dB is a function of the rate (X(rate0), X(rate1), X(rate2),X(rate 3), X(rate4), X(rate5), X(rate 6), X(rate7)) and may be differentfrom one rate to the next, e.g., X(rate0) dB>X(rate1) dB. In someembodiments, as rate increases, the transmission power level foruser/data modulation symbols also increases, and the power differenceX(rate) may decrease. The power difference X(rate) dB may be selected tobe sufficient to distinguish the signals conveying the additional energyfrom those without the additional energy. In some embodiments, e.g.,embodiments, where at least one of the rates is a QAM rate, differentadditional power level differences may exist for different amplitudelevels within the QAM rate. By varying the additional power level as afunction of rate (as shown in Table 1506), WT power can be conservedover methods where a fixed power difference is used (as shown in Table1500) which has been set to a specified worst case condition based onone level.

The method described with respect to exemplary tables 1500 and 1506 maybe applicable in embodiments such as those illustrated with theexemplary uplink traffic segment of FIG. 8.

FIG. 17 is a table 1700 illustrating an exemplary relationship betweenbase station selected maximum rate indicators and data rates that awireless terminal can select in another exemplary embodiment of thepresent invention. First row 1702 identifies that columns (1714, 1716,1718) include base station selected maximum rate indicator valueinformation, while columns (1720, 1722, 1724, 1726, 1728, 1730, 1732,1734, 1736, 1738, 1740, 1742, 1744, 1746, 1748, 1750) includeinformation identifying data rates that a WT can select, given a BSselected maximum rate indicator value. Second row 1704 identifies that:1^(st) column 1714 includes BS selected maximum rate indicator values,2^(nd) column 1716 includes the corresponding most significant bit (MSB)value, and third column 1718 includes the corresponding leastsignificant bit (LSB) value. Fourth through nineteenth columns (1720,1722, 1724, 1726, 1728, 1730, 1732, 1734, 1736, 1738, 1740, 1742, 1744,1746, 1748, 1750) correspond to data rates (15, 14, 13, 12, 11, 10, 9,8, 7, 6, 5, 4, 3, 2, 1, 0) supported by WTs in the system, where datarate 15 corresponds to the highest data rate and data rate 0corresponding to the lowest data rate.

In this exemplary embodiment a BS can select one of four maximum rateindicator values, which can be represented using two bits. Sixteendifferent rates are possible for WTs in the system which would require 4bits to represent each potential rate. However, each of the four maximumrate indicator values is associated with a maximum rate and a differentsubset of potential rates that the wireless is allowed to select from,each subset corresponding to a specific one of the four maximum rateindicators. In this example, each subset of data rates includes 8different data rates which may be represented by three bits. When thewireless terminal selects a data rate from the designated subset of 8rates as indicated by the received maximum rate indicator value, theselected rate can be encoded using 3 bits, with the coded bits havingdifferent representations depending upon the rate indicator value.

In this exemplary embodiment, different BS selected maximum rateindicator values may correspond to the same maximum data rate butdifferent subsets of data rates which may be selected by the wirelessterminal. Members of a subset are indicated by Xs in the columncorresponding to the data rate. Thus two maximum rate indicators maycorrespond to the same maximum data rate but can be used to restrict awireless terminal to select from different subsets of rates, where theWT is allowed to select a rate within the subset of rates correspondingto a received maximum rate indicator where the selected rate is lessthan or equal to the maximum allowed data rate.

Row 1706 indicates that BS selected maximum data rate indicator value 0corresponds to a maximum data rate of 15 and the subset of data rates(15, 13, 11, 9, 7, 5, 3, 0). Row 1708 indicates that BS selected maximumdata rate indicator value 1 corresponds to a maximum data rate of 15 andthe subset of data rates (15, 14, 13, 12, 11, 10, 9, 8). Row 1710indicates that BS selected maximum data rate indicator value 2corresponds to a maximum data rate of 11 and the subset of data rates(11, 10, 9, 8, 7, 6, 5, 4). Row 1712 indicates that BS selected maximumdata rate indicator value 3 corresponds to a maximum data rate of 7 andthe subset of data rates (7, 6, 5, 4, 3, 2, 1, 0).

FIG. 18 is a drawing 1800 illustrating a portion of an exemplary uplinktraffic segment, and the concentration of additional energy on a subsetof tone-symbols within the dwell to convey the uplink data rate used forthe segment, in accordance with an exemplary embodiment of the presentinvention. In the FIG. 18 example and the FIG. 19 example which follows,there is at least a 2 db energy difference between the symbol on whichadditional energy is placed and the symbols which the additional energyis not placed. This facilitates detection through a relatively simple toimplement energy detection mechanism which is based on identifyingsymbols with additional energy.

FIG. 18 plots logical tone index in exemplary uplink traffic channelsegment 0 on the vertical axis 1802 vs time (OFDM symbol index withinthe segment) on horizontal axis 1804. The exemplary segment is dividedinto four dwells are shown in FIG. 18 (dwell 1 1806, dwell 2 1808, dwell3 1810, dwell 4 1812), each dwell in the FIG. 18 example includes 7successive OFDM symbol time intervals. In accordance with one feature ofthe particular exemplary embodiment of the invention, for eachindividual tone used in a dwell in the segment, additional energy isplaced on the individual tone for one of the 7 symbol time periodsduring the dwell. The symbol time period in which the energy is placedto indicate the rate depends on the rate to be indicated and theposition of the tone in the set of tones which correspond to the dwell.Thus, by knowing the tone position within the set of tones assigned to awireless terminal and the symbol time within the dwell of the tonehaving the additional energy, it is possible to determine the rate whichis being communicated. While the rate can be determined by monitoring asingle tone of a dwell to determine the symbol time within the dwell atone with additional energy used to indicate rate information isreceived, greater reliability can be achieved by monitoring multipletones used by a wireless terminal in a dwell. Significantly, because thephysical tones used are changed at dwell boundaries, within the dwell,the channel conditions will normally remain relatively constant allowingcomparisons of the energy of received symbols to be compared in areliable manner for the duration of the dwell in most cases. While eachdwell is shown as including 7 symbol times and a segment including 7tones, the number of symbol times and segments per dwell could bedifferent depending on the particular implementation.

The exemplary segment may be divided into sub-blocks. Exemplarysub-block 1820 is shown in FIG. 18. In the segment, there are 28sub-blocks of which 16 are shown in FIG. 18. The exemplary uplinktraffic segment illustrated by grid 1800 may represent exemplary trafficsegment 0 in an exemplary timing and frequency structure being used inthe wireless communications system. The basic unit of the segment is atone-symbol represented by a small square, each tone-symbol occupyingone tone for a duration of one OFDM symbol time interval. A modulationsymbol may be conveyed on each tone-symbols of the segment.

In accordance with the present invention, a pattern of locations whereadditional energy is concentrated on a subset of signals within thesegment identifies the uplink data rate used by the WT for transmissionof the uplink traffic channel segment. Different data rates may be usedby the WT. In the exemplary embodiment of FIG. 18, the pattern of eachsub-block within the segment should be identical for a given data rate.

Legend 1814 indicates that tone-symbols of type 1816 represented withcrosshatch shading are part of a pattern corresponding to WT selecteddata rate 0, while tone-symbols of type 1818 represented with horizontalline shading correspond to WT selected data rate 2. For rate 0, the maindiagonals of each sub-block will have additional energy. For rate 2, theentries at positions offset −2 from the main diagonal of each sub-blockwill have additional energy. In general, consider a sub-block indexed as7×7 entries (0,0), . . . (6,6). Then for rate i, each of the entries atposition (k+i, k mod 7) for k=0, 1, 2, . . . , 6 has additional energy.For example, for rate 2, entries (2,0), (3,1), (4,2), . . . , (1, 6)have additional energy, as shown in FIG. 18.

FIG. 18 illustrates two exemplary cases of different WT uplink selecteddata rates on the same grid 1800. Consider that the WT has selected touse data rate 0, then for sub-block 1820, additional energy is placed onthe signals corresponding to tone symbols: (tone0, OFDM symbol index 1),(tone 1, OFDM symbol index 2), (tone 2, OFDM symbol index 3), (tone 3,OFDM symbol index 4), (tone4, OFDM symbol index 5), (tone 5, OFDM symbolindex 6), (tone 6, OFDM symbol index 7), while the other tone-symbols ofthe sub-block convey signals with nominal energy levels. Now considerthat the WT has selected to use data rate 2, then additional energy isplaced on the signals corresponding to tone symbols: (tone2, OFDM symbolindex 1), (tone 3, OFDM symbol index 2), (tone 4, OFDM symbol index 3),(tone 5, OFDM symbol index 4), (tone6, OFDM symbol index 5), (tone 0,OFDM symbol index 6), (tone 1, OFDM symbol index 7), while the othertone-symbols of the sub-block convey signals with nominal energy levels.The pattern corresponding to the rate is repeated for each sub-block ofthe segment. Other exemplary data rates, e.g., data rate 1 and data rate3 may be indicated by different patterns. In some embodiments, each ofthe patterns represents the same slope within the grid, but with adifferent offset. In some embodiments, the different patterns may berepresented by different slopes and/or including different offsetswithin the grid.

FIG. 19 is a drawing 1900 illustrating a portion of an exemplary uplinktraffic segment including tone-symbols used to convey modulation symbolsconveying information bits and tone-symbols used to convey referencemodulation symbols, and the concentration of additional energy on asubset on tone-symbols within the dwell to convey the uplink data rateused for the segment, in accordance with the present invention. FIG. 1plots logical tone index in exemplary uplink traffic channel segment 0on the vertical axis 1902 vs time (OFDM symbol index within the segment)on horizontal axis 1904. The exemplary segment is further divided fourdwells which are shown (dwell 1 1906, dwell 2 1908, dwell 3 1910, dwell4 1912), each dwell including 7 successive OFDM symbol time intervals.The exemplary uplink traffic segment illustrated by grid 1900 mayrepresent an exemplary traffic segment 0 of a timing and frequencystructure used in a wireless communications system. The basic unit ofthe segment is a tone-symbol represented by a small square, eachtone-symbol occupying one tone for a duration of one OFDM symbol timeinterval. A modulation symbol may be conveyed on each tone-symbol of thesegment.

In accordance with the present invention, a pattern of locations whereadditional energy is concentrated on a subset of signals within thesegment identifies the uplink data rate used by the WT for transmissionof the uplink traffic channel segment. The segment is subdivided insub-blocks, e.g., exemplary sub-block 1923. The additional energypattern repeats from sub-block to sub-block within the segment.Different data rates may be used by the WT and may correspond todifferent additional energy patterns.

Legend 1914 indicates that tone-symbols of type 1916 represented withcrosshatch shading are part of a pattern of modulation symbols withadditional energy corresponding to WT selected data rate 0; informationbits are conveyed in tone-symbols of type 1916 using data rate 0, datarate 0 signifying a coding rate and/or a modulation scheme. Legend 1914also indicates modulation symbols at normal energy level conveyinginformation bits at data rate 0 are conveyed in tone-symbols of type1918 as indicated by no shading. In addition legend 1914 indicates thattone-symbols of type 1919 are used to convey reference modulationsymbols. Legend 1914 indicates that tone-symbols of type 1921represented with vertical line shading are part of a pattern ofmodulation symbols with additional energy corresponding to WT selecteddata rate 0; reference modulation symbol values are conveyed intone-symbols of type 1921, data rate 0 signifying a coding rate and/or amodulation scheme.

FIG. 20 is a drawing 2000 of an exemplary uplink traffic channel segment2002, in accordance with the present invention. Vertical axis 2004 plotslogical tone index of the uplink traffic channel segment 2002 whichranges from 0 to 27; horizontal axis 2006 plots OFDM symbol time indexwithin the traffic channel segment 2002 which ranges from 1 to 28.Exemplary uplink traffic channel segment 2002 includes 784 tone-symbolsrepresented by small boxes. A tone-symbol is a transmission unit. Thetone-symbols are further grouped, as illustrated in FIG. 20, into 112tone half-slots (tone-halfslot k=0 2008, tone-halfslot k=111 2010). Atone-halfslot includes 7 tone-symbols in a halfslot. The tone-symbols ina half-slot have the same prehopping index and posthopping index, whichis kept constant over the halfslot.

FIG. 21 is a drawing 2100 of an exemplary uplink traffic channel segment2102, in accordance with the present invention. Vertical axis 2104 plotslogical tone index of the uplink traffic channel segment 2102 whichranges from 0 to 13; horizontal axis 2106 plots OFDM symbol time indexwithin the traffic channel segment 2102 which ranges from 1 to 56.Exemplary uplink traffic channel segment 2102 includes 784 tone-symbolsrepresented by small boxes. The tone-symbols are further grouped, asillustrated in FIG. 21, into 112 tone half-slots (tone-halfslot k=02108, tone-halfslot k=111 2110.

FIG. 22 is a drawing 2200 of an exemplary uplink traffic channel segment2202, in accordance with the present invention. Vertical axis 2204 plotslogical tone index of the uplink traffic channel segment 2202 whichranges from 0 to 6; horizontal axis 2206 plots OFDM symbol time indexwithin the traffic channel segment 2202 which ranges from 1 to 112.Exemplary uplink traffic channel segment 2202 includes 784 tone-symbolsrepresented by small boxes. The tone-symbols are further grouped, asillustrated in FIG. 22, into 112 tone half-slots (tone-halfslot k=02208, tone-halfslot k=111 2210.

FIG. 23 is a table 2300 of exemplary uplink traffic channel rateinformation, in accordance with various embodiments of the presentinvention. First column 2302 lists eight exemplary uplink trafficchannel rate options (0, 1, 2, 3, 4, 5, 6, 7). Second column 2304 liststhe corresponding framing format type for each of the rate options(first, first, first, first, first, second, second, second). Thirdcolumn 2306 lists the number of MAC frames corresponding to each of therate options (1, 2, 3, 4, 5, 6, 8, 10). Fourth column 2308 lists thenumber of information bits (k) corresponding to each of the rate options(224, 432, 640, 848, 1056, 1280, 1696, 2112. Fifth column 2310 lists thecodeword length (n) corresponding to each of the rate options (1344,1344, 1344, 1344, 1344, 2688, 2688, 2688). Sixth column 2312 list themodulation constellation used for each of the corresponding rate options(QPSK, QPSK, QPSK, QPSK, QPSK, QAM16, QAM16, QAM16).

FIG. 24 is a table 2400 illustrating exemplary mapping between an uplinktraffic channel segment in-band indicator X and uplink traffic channelrate option values. First column 2402 lists the seven different values(0, 1, 2, 3, 4, 5, 6) that the uplink traffic channel segment in-bandindicator X may have in the exemplary embodiment. Second column 2404lists the corresponding rate options for each of the uplink trafficchannel segment in-band indicator values for the cases where thewireless terminal has not been assigned a maximum rate indicator for thesegment indicating that the maximum rate option (7) may be selected foruse by the WT, and the assignment has been a regular assignment. Forexample, if a WT has been assigned, via a regular assignment, an uplinktraffic channel segment to use and a maximum rate indicator valueindicating that the highest allowable rate for the WT to use is rateoption 6, then, the WT may select a rate option less than or equal tothe maximum indicated allowable rate option from column 2404, e.g.,based on the WTs current needs and WT determined conditions. Forexample, consider under such conditions, that the WT selects to use rateoption 4 for the uplink traffic channel segment, then columns 2404 and2402 of table 2400 indicates to the WT that the corresponding uplinktraffic channel segment in-band indicator X should be a value of 4.

Third column 2406 lists the corresponding rate options for each of theuplink traffic channel segment in-band indicator values for the casewhere the wireless terminal has been assigned, via a regular assignment,a maximum rate indicator for the segment indicating that the maximumrate option (7) may be selected for use by the WT. For example, if a WThas been assigned an uplink traffic channel segment to use and a maximumrate indicator value indicating that the highest allowable rate for theWT to use is rate option 7, then, the WT may select a rate option lessthan or equal to the maximum indicated allowable rate option from column2406, e.g., based on the WTs current needs and WT determined conditions.Note, that in this exemplary embodiment rate option 4 has been precludedfrom selection. For example, under such conditions, consider that the WTselects to use rate option 6 for the uplink traffic channel segment,then columns 2406 and 2402 of table 2400 indicates to the WT that thecorresponding uplink traffic channel segment in-band indicator X shouldbe a value of 5.

In addition, third column 2406 is used in the case where the uplinktraffic channel segment assignment has been conveyed via a flashassignment.

The WT and base station both store the information represented in tables2300 and 2400. The uplink traffic channel segment in-band indicator iscommunicated to the base station in the uplink traffic channel segment.The base station, having sent the maximum uplink rate indicator to theWT for the given assigned uplink traffic channel segment, and knowingwhether the assignment was a regular assignment or a flash assignment,knows which column of table 2400 to use when interpreting a received anddetermined uplink traffic channel segment in-band indicator X, such thatthe base station can make the proper association and determine theuplink traffic channel rate option selected by the WT and being used bythe WT for the segment.

FIG. 25 includes a drawing of an exemplary tone half-slot k 2500, inaccordance with the present invention. Exemplary tone half-slot k 2500may be any of the tone-half slots of the different exemplary uplinktraffic channel segments of FIG. 20, 21, or 22. Exemplary tone-halfslotk 2500 includes 7 successive OFDM tone-symbols (tone symbol withrelative index j=0 2502, tone-symbol with relative index j=1 2504,tone-symbol with relative index j=2 2506, tone symbol with relativeindex j=3 2508, tone symbol with relative index j=4 2510, tone symbolwith relative index j=5 2512, tone symbol with relative index j=6 2514).

FIG. 25 also includes table 2550 indicating WT uplink traffic channelsegment modulation symbol scaling. For each tone-halfslot of an uplinktraffic channel segment one of two level of modulation symbol scalingare used. First row 2552 indicates that S2 modulation symbol scaling isused for the one tone symbol of tone-half slot k with relative indexvalue j, where j=mod (k+X, 7). Second row 2554 indicates that S1modulation symbol scaling is used for the other six tone symbol oftone-half slot k.

Each tone-symbol of an assigned uplink traffic channel segment mayconvey a modulation symbol. Any modulation symbol of the uplink trafficchannel segment shall be scaled using either S1 or S2 scaling. Whetherto use S1 or S2 scaling for a given modulation symbol shall depend uponthe tone-symbol to which the modulation symbol is mapped in theoperation of segment mapping. In a given uplink traffic channel segment,a subset of tone-symbols uses S2 scaling and the subset of the remainingtone-symbols in the segment is to use S1 scaling. The partition intothose two subsets depends upon the uplink traffic channel segmentin-band indicator X, which is determined by the WT as a function of theBS assigned maximum rate option that may used for the segment and theactual rate being used for the segment, said actual rate being usedhaving been selected by the WT.

In some embodiments, S1 denotes a wireless terminal relative channelpower scaling factor for the uplink traffic channel segment expressed indB, and S2 is set to a value larger than S1, e.g., S2=S1+2.67, whereboth S1 and S2 are expressed in dBs. In some such embodiments, thescaling factors using S1 and S2 are equal to SQRT (WT Nominal PowerLevel)*10^((S1/20)) and SQRT(WT Nominal Power Level)*10^((S2/20)),respectively. The WT Nominal Power level represents the WT nominal pertone transmission power in dBm, and the value of the WT Nominal Power,in some embodiments, is determined using methods including closed looppower control between the WT and the base station. In some embodiments,the value of S1 is determined as a function of the rate option, e.g.,for rate option (0, 1, 2, 3, 4, 5, 6, 7), the corresponding value of S1is (−1.4, 1.1, 2.9, 4.8, 6.7, 8.7, 10.7, 12.9) expressed in dBs.

Consider the example of FIG. 26. FIG. 26 illustrates an exemplary uplinktraffic channel segment 2602. The structure of the exemplary trafficchannel segment 2602 may be that of exemplary traffic channel segment2002 of FIG. 20, 28 tones×28 OFDM tone symbol indexes, further dividedinto 112 ordered tone-halfslots. Consider that the WT has decided to useuplink channel rate option 0. The WT determines, e.g., from table 2400,that the uplink traffic channel segment in-band indicator X will be setto 0. Then for each tone-half slot k, k=0, 111 of segment 2602, the WTdetermines which one tone-symbol, in terms of relative index value j forthe given tone-half-slot k, is to be assigned the S2 level of modulationsymbol scaling. Information included in table 2550 can be used in thedetermination. Legend 2604 indicates that OFDM tone-symbols as indicatedwith crosshatch shading 2606 are to use scaling factor S2, whiletone-symbols as indicated with no shading 2608 are to use scaling factorS1.

Consider the example of FIG. 27. FIG. 27 illustrates an exemplary uplinktraffic channel segment 2702. The structure of the exemplary trafficchannel segment 2702 may be that of exemplary traffic channel segment2102 of FIG. 21, 14 tones×56 OFDM tone symbol indexes, further dividedinto 112 ordered tone-halfslots. Consider that the WT has decided to useuplink channel rate option 2. The WT determines, e.g., from table 2400,that the uplink traffic channel segment in-band indicator X will be setto 2. Then for each tone-half slot k, k=0, 111 of segment 2702, the WTdetermines which one tone-symbol, in terms of relative index value j forthe given tone-half-slot k, is to be assigned the S2 level of modulationsymbol scaling. Information included in table 2550 can be used in thedetermination. Legend 2704 indicates that OFDM tone-symbols as indicatedwith crosshatch shading 2706 are to use scaling factor S2, whiletone-symbols as indicated with no shading 2708 are to use scaling factorS1.

The uplink traffic channel segment in-band indicator X and the tonehalf-slot values k within the uplink traffic channel segment determinethe mapping of S2 and S1 scaling for the segment. It should be notedthat uplink traffic segment in-band indicator X, when it is a value of4, 5, or 6 may indicate two different uplink rates options, dependingupon the value of the maximum uplink rate allowed as communicated fromthe base station to the WT and/or the type of assignment regular orflash.

Now consider the example of FIG. 28. FIG. 28 illustrates an exemplaryuplink traffic channel segment 2802. The structure of the exemplarytraffic channel segment 2802 may be that of exemplary traffic channelsegment 2102 of FIG. 21, 14 tones×56 OFDM tone symbol indexes, furtherdivided into 112 ordered tone-halfslots. Consider that the BS assignedmaximum rate option indicator indicated a maximum uplink rate option of5 or 6, the assignment was via a regular assignment, and the WT decidedto use uplink rate option 5. Alternately consider that the maximum rateoption indicator indicated a maximum uplink rate option of 7, theassignment was via a regular assignment, and the WT decided to use rateoption 6. Alternately, consider that the maximum rate option indicatorindicated a maximum uplink rate option of 7, the assignment was via aflash assignment, and the WT decided to use uplink rate option 6. Forany of the abovementioned scenarios, the WT determines, e.g., from table2400, that the uplink traffic channel segment in-band indicator X willbe set to 5. Then for each tone-half slot k, k=0, 111 of segment 2802,the WT determines which one tone-symbol, in terms of relative indexvalue j for the given tone-half-slot k, is to be assigned the S2 levelof modulation symbol scaling. Information included in table 2550 can beused in the determination. Legend 2804 indicates that OFDM tone-symbolsas indicated with crosshatch shading 2806 are to use scaling factor S2,while tone-symbols as indicated with no shading 2808 are to use scalingfactor S1.

For a given uplink traffic channel segment in various above describedembodiments, each tone-halfslot conveys the same uplink traffic channelsegment in-band indicator and thus same rate option information. Byutilizing each of the tone-half slots of the segment to convey the rateoption information, the difference in power level between the twomodulation symbol scaling factors used for the segment can be set at alower level than would otherwise be needed to accomplish the same levelof detection capability if the rate option information were onlyconveyed on some of the tone-half slots of the segment. In some otherembodiments, a portion, of the uplink traffic channel is used to conveyuplink rate option information for the segment using the methods of thepresent invention, while a different portion of the uplink trafficchannel segment is not used to convey uplink rate option information forthe segment.

FIG. 29 includes table 2900 illustrating two types of uplink trafficchannel assignment signaling techniques, in accordance with the presentinvention. In some embodiments, different coding and/or modulationtechniques are used for the different assignment signaling techniques.First column 2902 lists the type of downlink traffic control sub-channelused for assignment of uplink traffic channel segment, regular or flash.Second column 2904 includes WT assignment identification informationincluding field name information and the number of bits corresponding tothe field. Third column 2906 includes maximum rate information includingfield name information and the number of bits corresponding to thefield. Row 2908 includes information identifying that a regular downlinktraffic control sub-channel segment being used to provide assignmentinformation for an uplink traffic channel segment includes an ON IDfield of 5 bits used to identify the WT to which the assignment isdirected and a rate option field of 3 bits used to identify the maximumrate option that the assigned WT is allowed to use in the correspondingassigned uplink traffic channel segment. Row 2910 includes informationidentifying that a flash downlink traffic control sub-channel segmentbeing used to provide assignment information for an uplink trafficchannel segment includes an ON ID field of 5 bits used to identify theWT to which the assignment is directed and a congestion indicator fieldof 1 bit used to convey information from the BS to the WT that can beused by the WT to identify the maximum uplink rate option that theassigned WT is allowed to use in the corresponding assigned uplinktraffic channel segment.

FIG. 29 also includes table 2930 which provides additional informationfurther identifying the maximum rate option information conveyed in therate option field of the regular DL traffic control sub-channel segmentfor a corresponding uplink traffic channel segment. First column 2902lists the rate option value (0, 1, 2, 3, 4, 5, 6, 7) which can beconveyed by the 3 bit value of the rate option field. Second column 2904lists the information conveyed from the BS to the WT by each rate optionvalue. Rate option value (0, 1, 2, 3, 4, 5, 6, 7) conveys that themaximum WT uplink rate option that the WT is allowed to use for thecorresponding uplink traffic channel segment is rate option (0, 1, 2, 3,4, 5, 6, 7), respectively.

FIG. 29 also includes table 2950 which provides additional informationfurther identifying the maximum rate option information conveyed in thecongestion indicator field of the flash DL traffic control sub-channelsegment for a corresponding uplink traffic channel segment. First column2952 lists the congestion indicator values (0, 1) which can be conveyedby the one bit value of the congestion indicator field. Second column2954 lists the information conveyed from the BS to the WT by eachcongestion indicator value. The congestion indicator value indicates amaximum wireless uplink rate option that may be used by the WT for thecorresponding uplink traffic channel segment. For example, a congestionindicator value of 0 indicates that the WT is allowed a maximum uplinkrate option of 3, subject to additional constraints imposed at the WT; acongestion indicator value of 1 indicates that the WT is allowed amaximum uplink rate option of 7, subject to additional constraintsimposed at the WT. The WT performs beacon measurements and generates ageneric beacon ratio report. The congestion indicator value, inaccordance with the present invention, takes on different meanings as afunction of a condition report, e.g., the generic beacon ratio report,performed by the WT. The condition report can be, e.g., a generic beaconratio report, i.e., the ratio of the received power of the downlinkbeacon signal of the serving base station sector, with respect to theWT, and the sum of the received powers of the downlink beacon signals ofeach of the other interfering base station sectors, as determining bythe WT receiving the beacon signals. The output values of the beaconratio report may be quantized, e.g., into the following possible levels−6 dB, −4 dB, −2 dB, 0 dB, 1 dB, 2 dB, 3 dB, 4 dB, 6 dB, 8 dB, 10 dB, 12dB, 14 dB, 16 dB, 18 dB, 20 dB. If the congestion indicator value is 0and the generic beacon ratio report sent from the WT indicates a ratioless than 1 dB, then the maximum WT uplink rate option that the WT isallowed to use for the corresponding uplink traffic channel segment israte option 0. If the congestion indicator value is 0 and the genericbeacon ratio report indicates a ratio from 1 dB to 4 dB, then themaximum WT uplink rate option that the WT is allowed to use for thecorresponding uplink traffic channel segment is rate option 1. If thecongestion indicator value is 0 and the generic beacon ratio report sentfrom the WT indicates a ratio from 6 to 12 dB, then the maximum WTuplink rate option that the WT is allowed to use for the correspondinguplink traffic channel segment is rate option 2. If the congestionindicator value is 0 and the generic beacon ratio report indicates aratio greater than 12 dB, then the maximum WT uplink rate option thatthe WT is allowed to use for the corresponding uplink traffic channelsegment is rate option 3. If the congestion indicator value is 1 and thegeneric beacon ratio report sent from the WT indicates a ratio less than1 dB, then the maximum WT uplink rate option that the WT is allowed touse for the corresponding uplink traffic channel segment is rate option3. If the congestion indicator value is 1 and the generic beacon ratioreport indicates a ratio from 1 dB to 4 dB, then the maximum WT uplinkrate option that the WT is allowed to use for the corresponding uplinktraffic channel segment is rate option 3. If the congestion indicatorvalue is 1 and the generic beacon ratio report sent from the WTindicates a ratio from 6 to 12 dB, then the maximum WT uplink rateoption that the WT is allowed to use for the corresponding uplinktraffic channel segment is rate option 5. If the congestion indicatorvalue is 1 and the generic beacon ratio report indicates a ratio greaterthan 12 dB, then the maximum WT uplink rate option that the WT isallowed to use for the corresponding uplink traffic channel segment israte option 7.

FIG. 30 includes Table 3000 corresponding to exemplary QPSKconstellation mapping and table 3050 corresponding to exemplary QAM16constellation mapping. Table 3000 includes exemplary QPSK constellationmapping using scale factor 1.000000 and shows four exemplary bitpatterns (00, 01 ,10, 11) mapped to complex symbols ((1,1), (1,−1),(−1,1) and (−1,−1)), respectively. Table 3000 illustrates that for QPSKmapping, for a given scale factor applied, each of the four potentialmodulation symbols will have the same output level in terms of magnitudeof the complex symbol, e.g., scale factor 1.000000 with each of the fourmodulation symbols having a magnitude of sqrt (2). Therefore when QPSKconstellation mapping is used for an uplink traffic channel segment andtwo scaling factors are used, in accordance with the present invention,to convey rate option information, the margin in terms of power level indB between modulation symbols of the two subsets is uniform, e.g., anymodulation symbol of the segment using the lower scaling has the samepower difference in terms of dB than any other modulation symbol of thesegment using the higher scaling.

Table 3050 includes exemplary QAM16 constellation mapping using scalefactor 1/sqrt(5)=0.447214 and shows 16 exemplary bit patterns (0000,0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100,1101, 1110, 1111) mapped to complex symbols ((1,−3,3), (−3,1),respectively, which are scaled by 0.447214. Table 3050 illustrates thatfor QAM16 mapping, for a given scale factor applied, a first set of fourpotential modulation symbols will have the same first output level interms of magnitude of the complex symbol, a second set of four potentialmodulation symbols will have the same second output level in terms ofmagnitude of the complex symbol, and a third set of eight potentialmodulation symbols will have the same third output level in terms ofmagnitude of the complex symbol. For example, consider bit pattern(0011) which corresponds to complex symbol (1/sqrt(5), 1/sqrt(5)) whichis a member of the first set with magnitude sqrt(2/5); bit pattern(0100) which corresponds to complex symbol (3/sqrt(5),−3/sqrt(5)) is amember of the second set with magnitude sqrt(18/5); bit pattern (0000)which corresponds to complex symbol (1/sqrt(5),−3/sqrt(5)) is a memberof the third set with pre-scaling magnitude sqrt(10/5). Therefore whenQAM16 constellation mapping is used for an uplink traffic channelsegment the actual power used for transmission for a given modulationsymbol or for the composite of modulation symbols for the segment isdependent upon the bit pattern(s) being communicated. In addition, whentwo scaling factors are used, in accordance with the present invention,to convey rate option information, the actual energy margin for a givensegment is dependent upon the data pattern being communicated. Note thatscaling factors S1 and S2, each representing a single value to be usedfor different subsets of the same given segment, are set on a per tonebasis for a given average segment. The actual bit pattern for a givensegment can alter the ability to successfully recover the rate optioninformation conveyed by the energy differences when using QAM16modulation. However, retransmission methods for unsuccessfully recoveredsegments, in accordance with the present invention, typically change thetransmission bit pattern, when conveying the same information,increasing the likelihood that the rate option information will besuccessfully recovered in the retransmission.

FIG. 31 is a drawing 3100 illustrating exemplary assignments andexemplary corresponding uplink traffic channel segments. Horizontal axis3102 represents time. Two types of assignments are shown a regular typeassignment and a flash type assignment, each type of assignment using adifferent coding and modulation method. In some embodiments, the powerlevel of flash assignments signals is higher than the power level ofregular assignment signals for a given base station. The exemplaryregular type assignment includes 3 bits for specifying a maximum rateindicator value, allowing the regular type assignment to distinguishbetween 8 different values corresponding to eight different maximum rateindicator options, e.g., one for each of the uplink rate optionssupported by the system, e.g., rate option 0, 1, 2, 3, 4, 5, 6, 7. Theexemplary flash type assignment includes 1 bit for specifying a maximumrate indicator value, allowing the flash type assignment to distinguishbetween 2 different values corresponding to two maximum rate indicatoroptions, e.g., one corresponding to the highest uplink rate optionsupported by the system, e.g., rate option 7, and one corresponding toan intermediate uplink rate option supported by the system, e.g., rateoption 3. Each of the assignments (regular assignment 3102, regularassignment 3104, regular assignment 3106, flash assignment 3108, regularassignment 3110, flash assignment 3112) is associated with acorresponding uplink traffic channel (UL TCH) segment (UL TCH segment 13502, UL TCH segment 2 3504, UL TCH segment 3 3506, UL TCH segment 43508, UL TCH segment 5 3510, UL TCH segment 6 3512), respectively. Thebasic timing/frequency structure and association between assignments anduplink traffic channel segments repeats on a periodic basis. Theassignments including the maximum rate indicator information istransmitted by the base station according to a predetermined periodictransmission schedule having a fixed timing relationship to the uplinksegments being assigned. Assignments (regular assignment 3102′, regularassignment 3104′, regular assignment 3106′, flash assignment 3108′,regular assignment 3110′, flash assignment 3112′) associated withcorresponding uplink traffic channel (UL TCH) segments (UL TCH segment 13502′, UL TCH segment 2 3504′, UL TCH segment 3 3506′, UL TCH segment 43508′, UL TCH segment 5 3510′, UL TCH segment 6 3512′), respectively,represents a repeat of the set of assignments (3102, 3104, 3106, 3108,3110, 3112) and corresponding uplink traffic channel segments (3502,3504, 3506, 3508, 3510, 3512). In the example of FIG. 30 there are sixuplink traffic channel segments in the repetitive structure. In otherembodiments, there may be a different numbers of uplink traffic channelsegments in the repetitive structure, e.g., 77 indexed uplink trafficchannel segments in a timing and frequency structure with 49 of theindexed uplink traffic channel segments corresponding to regularassignments and 28 of the indexed uplink traffic channel segmentscorresponding to flash assignments.

FIG. 32 is a flowchart 3200 of an exemplary method of operating awireless terminal in a wireless communications system, in accordancewith the present invention. For example, the wireless communicationssystem may be an OFDM spread spectrum multiple access wirelesscommunications system in which the base station signals a maximum uplinkrate indicator value for an uplink traffic channel segment, and the WTtransmits data in the assigned uplink traffic channel segment using aselected data rate option which is less than or equal to the receivedindicated maximum uplink data rate option. In such an exemplary OFDMsystem, the basic transmission unit may be an OFDM tone symbolrepresenting the air link resource associated with one tone for theduration of one OFDM symbol transmission time interval.

The method of operation starts in step 3202, where the WT is powered onand initialized. In step 3202, the WT may register with one of aplurality of base stations in the system, e.g., the base stationcorresponding to the cell in which it is currently located, and betransitioned into an ON state of operation, e.g., receiving a basestation assigned wireless terminal identifier. Operation proceeds fromstep 3202 to step 3204.

In step 3204, the WT is operated to receive an uplink traffic channelassignment including a maximum rate option indicator value correspondingto an uplink traffic channel segment, e.g., an uplink traffic channelsegment in an uplink timing/frequency structure including a fixed numberof predetermined indexed traffic channel segments which repeat on arecurring basis. Then, in step 3206 the WT determines whether thereceived assignment is for the WT or for another WT registered with thebase station, e.g., by examining the contents of an WT identifier fieldincluded as part of the assignment information and comparing therecovered information to the WT's BS assigned WT identifier.

If the assignment is not intended for the WT, operation proceeds fromstep 3206 back to step 3204, where the WT receives and processes otherassignments. If the assignment is intended for the WT, operationproceeds from step 3206 to step 3208 for operations related to theassignment, and to step 3204 to receive and process additionalassignments.

In step 3208, the WT is operated to determine an indicator value for theassigned uplink channel segment, said indicator value indicating uplinkrate option information providing transmission rate information aboutthe data transmitted in the assigned uplink channel segment. Step 3208includes sub-step 3210 in which the WT determines whether the receivedmax rate option value is from a first set of values or a second set ofvalues. For example, with regard to the received maximum rate optionvalues, an exemplary first set of values may be the set of values {0, 1,2, 3, 4, 5, 6} and an exemplary second set of values may be the value{7}. If the received maximum rate option is from a first set of valuesthen operation proceeds to sub-step 3212, but if the received maximumrate option value is from a second set of values, operation proceeds tosub-step 3214.

In sub-step 3212 the WT selects a rate option less than or equal to thereceived maximum rate option value. Then, in sub-step 3216, the WTdetermines a mapping from the selected rate option to the indicatorvalue using a first function. In some embodiments, the first function isalso a function of the type of assignment, e.g., regular or flash,corresponding to the uplink channel segment. For example, an exemplaryfirst function mapping from selected rate option to indicator value maybe (0, 1, 2, 3, 4, 5, 6)→(0, 1, 2, 3, 4, 5, 6) corresponding to regulartype assignments, and (0, 1, 2, 3, 5, 6)→(0, 1, 2 , 3, 5, 6)corresponding to flash type assignments, and this mapping function maybe used by the WT in sub-step 3216.

In sub-step 3214, the WT selects a rate option less than or equal to thereceived maximum rate option value. Then, in sub-step 3218, the WTdetermines a mapping from the selected rate option value to theindicator value using a second function. For example an exemplary secondfunction mapping from selected rate option to indicator value may be (0,1, 2, 3, 5, 6, 7)→(0, 1, 2, 3, 4, 5, 6), and this mapping may be used bythe WT in sub-step 3218.

Operation proceeds from either sub-step 3216 or sub-step 3218 tosub-step 3220. In sub-step 3220, the WT is operated to indicate in theuplink channel segment, with the data, the determined uplink rate optioninformation. In some embodiments, sub-step 3220 includes sub-step 3222.In sub-step 3222, the wireless terminal uses an energy pattern withinthe segment to communicate the indicator value. In other embodiments,the indicator value, which is a mapped selected rate option value, isincluded in the uplink traffic channel segment signaling using adifferent method, e.g., a coded sub-block within the uplink trafficchannel segment conveying coded bits representing the indicator viamodulation symbol constellation values using a predetermined coding andmodulation scheme.

Operation proceeds from step 3208 to step 3224. In step 3224, the WT isoperated to transmit uplink signals using the air link resources of theassigned uplink channel segment, the uplink signals including the dataand the corresponding rate option information.

In some embodiments, the indicator value is one of N possible values andthe total number of uplink data rate options supported by the WT isgreater than N, where N is a positive integer greater than 1. Forexample N may be equal to 7 and the total number of uplink data rateoptions supported by the wireless terminal may be 8.

In various embodiments, an uplink segment includes a plurality oftransmission units, the indicator value is one of the N possibleindicator values, and each of the N possible indicator values correspondto a different subset of transmission units in the segment, and theindicator value is communicated by applying a higher power scale factorto the subset of the transmission units in said segment corresponding tothe indicator value being communicated. In some such embodiments, eachof the N different subsets of transmission units are non-overlappingwith each transmission unit corresponding to at most one of the Ndifferent subsets. In some such embodiments, all the transmission unitsin the segment are included in a set of subsets which is formed from thecombination of the N different subsets.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., 112tone-halfslots, each tone-halfslot including a predetermined number,e.g., seven, of temporarily consecutive tone-symbols corresponding tothe same tone, the tone-halfslots having a predetermined tone-halfslotindex value k, each tone-symbol within a tone half-slot being identifiedby a relative tone-symbol index j, the equation j=MOD (k+X, 7)identifying tone-symbols within the tone-halfslot which belong to thesubset of tone-symbols, corresponding to the one of the N indicatorvalues, one-tone symbol in each tone-halfslot corresponding to theindicator value being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to 6; where j is aninteger in the range 0 to 6; and k is an integer in the range of 0 tothe total number of tone-halfslots in the segment minus 1, e.g. 0 to111.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., 112tone-halfslots, each tone-halfslot including a predetermined number,e.g., seven, of temporarily consecutive tone-symbols corresponding tothe same tone, the tone-halfslots having a predetermined tone-halfslotindex value k, each tone-symbol within a tone half-slot being identifiedby a relative tone-symbol index j, the equation j=MOD (k−X, 7)identifying tone-symbols within the tone-halfslot which belong to thesubset of tone-symbols, corresponding to the one of the N indicatorvalues, one-tone symbol in each tone-halfslot corresponding to theindicator value being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to 6; where j is aninteger in the range 0 to 6; and k is an integer in the range of 0 tothe total number of tone halfslots in the segment minus 1, e.g., 0 to111.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., ntone-halfslots, each tone-halfslot including a predetermined number,e.g., m, of temporarily consecutive tone-symbols corresponding to thesame tone, the tone-halfslots having a predetermined tone-halfslot indexvalue k, each tone-symbol within a tone half-slot being identified by arelative tone-symbol index j, the equation j=MOD (k+X, m) identifyingtone-symbols within the tone-halfslot which belong to the subset oftone-symbols, corresponding to the one of the N indicator values,one-tone symbol in each tone-halfslot corresponding to the indicatorvalue being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to m−1; where j is aninteger in the range 0 to m−1; and k is an integer in the range of 0 tothe total number of tone halfslots in the segment minus 1, n−1, where nis a positive integer greater than or equal to two and m is a positiveinteger greater than or equal to four. In some such embodiments, m=7.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., ntone-halfslots, each tone-halfslot including a predetermined number,e.g., m, of temporarily consecutive tone-symbols corresponding to thesame tone, the tone-halfslots having a predetermined tone-halfslot indexvalue k, each tone-symbol within a tone half-slot being identified by arelative tone-symbol index j, the equation j=MOD (k−X, m) identifyingtone-symbols within the tone-halfslot which belong to the subset oftone-symbols, corresponding to the one of the N indicator values,one-tone symbol in each tone-halfslot corresponding to the indicatorvalue being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to m−1; where j is aninteger in the range 0 to m−1; and k is an integer in the range of 0 tothe total number of tone halfslots in the segment minus 1, n−1, where nis a positive integer greater than or equal to two and m is a positiveinteger greater than or equal to four. In some such embodiments, m=7.

FIG. 38 is a flowchart 3800 of an exemplary method of operating awireless terminal in a wireless communications system, in accordancewith the present invention. For example, the wireless communicationssystem may be an OFDM spread spectrum multiple access wirelesscommunications system in which the base station signals a maximum uplinkrate indicator value for an uplink traffic channel segment, and the WTtransmits data in the assigned uplink traffic channel segment using aselected data rate option which is less than or equal to the receivedindicated maximum uplink data rate option. In such an exemplary OFDMsystem, the basic transmission unit may be an OFDM tone-symbolrepresenting the air link resource associated with one tone for theduration of one OFDM symbol transmission time interval.

The method of operation starts in step 3802, where the WT is powered onand initialized. In step 3802, the WT may register with one of aplurality of base stations in the system, e.g., the base stationcorresponding to the cell in which it is currently located, and betransitioned into an ON state of operation, e.g., receiving a basestation assigned wireless terminal identifier. Operation proceeds fromstep 3802 to step 3804.

In step 3804, the WT is operated to receive an uplink traffic channelassignment including a maximum rate option indicator value correspondingto an uplink traffic channel segment, e.g., an uplink traffic channelsegment in an uplink timing/frequency structure including a fixed numberof predetermined indexed traffic channel segments which repeat on arecurring basis. Then, in step 3806 the WT determines whether thereceived assignment is for the WT or for another WT registered with thebase station, e.g., by examining the contents of an WT identifier fieldincluded as part of the assignment information and comparing therecovered information to the WT's BS assigned WT identifier.

If the assignment is not intended for the WT, operation proceeds fromstep 3806 back to step 3804, where the WT receives and processes otherassignments. If the assignment is intended for the WT, operationproceeds from step 3806 to step 3808 for operations related to theassignment, and to step 3804 to receive and process additionalassignments.

In step 3808, the WT is operated to determine an indicator value for theassigned uplink channel segment, said indicator value indicating uplinkrate option information providing transmission rate information aboutthe data transmitted in the assigned uplink channel segment. Step 3808includes sub-step 3810 in which the WT determines whether the receivedassignment was a first, e.g., regular type assignment, or second type ofassignment, e.g., a flash type assignment. If the received assignmentwas a first type of assignment, operation proceeds from sub-step 3810 tosub-step 3812, but if the received assignment was a second type ofassignment, operation proceeds from sub-step 3810 to sub-step 3814.

In sub-step 3812, the WT determines whether the received max rate optionvalue is from a first set of values or a second set of values. Forexample, with regard to the received maximum rate option values, anexemplary first set of values may be the set of values {0, 1, 2, 3, 4,5, 6} and an exemplary second set of values may be the value {7}. If thereceived maximum rate option is from a first set of values thenoperation proceeds to sub-step 3812, but if the received maximum rateoption value is from a second set of values, operation proceeds tosub-step 3818.

In sub-step 3816 the WT selects a rate option less than or equal to thereceived maximum rate option value and within a set of rate optionsassociated with the first set. For example, the WT may select an uplinkdata rate option within the set of rate options {0, 1, 2, 3, 4, 5, 6}which is less than or equal to the received maximum rate option valuecommunicated from the base station. Then, in sub-step 3820, the WTdetermines a mapping from the selected rate option to the indicatorvalue using a first function. For example, an exemplary first functionmapping from selected rate option to indicator value may be (0, 1, 2, 3,4, 5, 6)→(0, 1, 2, 3, 4, 5, 6) and this mapping function may be used bythe WT in sub-step 3820.

In sub-step 3818, the WT selects a rate option less than or equal to thereceived maximum rate option value and within a set of rate optionsassociated with the second set. For example, the WT may select an uplinkdata rate option within the set of rate options {0, 1, 2, 3, 5, 6, 7}which is less than or equal to the maximum rate option communicated tothe base station. Then, in sub-step 3822, the WT determines a mappingfrom the selected rate option value to the indicator value using asecond function. For example an exemplary second function mapping fromselected rate option to indicator value may be (0, 1, 2, 3, 5, 6, 7)→(0,1, 2, 3, 4, 5, 6), and this mapping may be used by the WT in sub-step3822.

In sub-step 3814, the WT selects a rate option less than or equal to thereceived maximum rate option value and within a set of rate optionsassociated with the second type of assignment. In some embodiments, theset of rate options associated with the second type of assignment is thesame as the set of rate options associated with the second set. Forexample, the WT may select an uplink data rate option within the set ofrate options {0, 1, 2, 3, 5, 6, 7} which is less than or equal to themaximum rate option communicated to the base station. In someembodiments, the selection of a rate option in step 3814 includes usinginterference information, e.g., a beacon ratio report. For example, thereceived maximum rate option value communicated from the base stationmay be subjected to a potential decrease as a function of interferencemeasurements performed by the WT resulting in a new maximum rate optionvalue less than or equal to the received maximum rate option value; thenthe WT selects a uplink data rate option to use, e.g., as a function ofthe amount of data to communicate and/or time critically of the data,the selected uplink data rate option being less than or equal to the newmaximum rate option value. Operation proceeds from step 3814 to step3824.

In sub-step 3824, the WT determines a mapping from the selected rateoption value to the indicator value using a third function. In someembodiments, the third function of step 3824 is the same as the secondfunction used in step 3822. For example an exemplary third functionmapping from selected rate option to indicator value may be (0, 1, 2, 3,5, 6, 7)→(0, 1, 2, 3, 4, 5, 6), and this mapping may be used by the WTin sub-step 3224.

Operation proceeds from sub-step 3820 or sub-step 3822 or sub-step 3824to sub-step 3826. In sub-step 3826, the WT is operated to indicate inthe uplink channel segment, with the data, the determined uplink rateoption information. In some embodiments, sub-step 3826 includes sub-step3828. In sub-step 3828, the wireless terminal uses an energy patternwithin the segment to communicate the indicator value. In otherembodiments, the indicator value, which is a mapped selected rate optionvalue, is included in the uplink traffic channel segment signaling usinga different method, e.g., a coded sub-block within the uplink trafficchannel segment conveying modulation symbol values using a predeterminedcoding and modulation scheme. In some such embodiments, the sub-blockconveying the indicator value may use a non-coherent modulation method,e.g., a combination of zero and non-zero QPSK modulation symbols, whilethe portion of the uplink segment conveying the coded user data may usea coherent modulation scheme.

Operation proceeds from step 3226 to step 3840. In step 3840, the WT isoperated to transmit uplink signals using the air link resources of theassigned uplink channel segment, the uplink signals including the dataand the corresponding rate option information.

In some embodiments, the indicator value is one of N possible values andthe total number of uplink data rate options supported by the WT isgreater than N, where N is a positive integer greater than 1. Forexample N may be equal to 7 and the total number of uplink data rateoptions supported by the wireless terminal may be 8.

In various embodiments, an uplink segment includes a plurality oftransmission units, the indicator value is one of the N possibleindicator values, and each of the N possible indicator values correspondto a different subset of transmission units in the segment, and theindicator value is communicated by applying a higher power scale factorto the subset of the transmission units in said segment corresponding tothe indicator value being communicated. In some such embodiments, eachof the N different subsets of transmission units are non-overlappingwith each transmission unit corresponding to at most one of the Ndifferent subsets. In some such embodiments, all the transmission unitsin the segment are included in a set of subsets which is formed from thecombination of the N different subsets.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., 112tone-halfslots, each tone-halfslot including a predetermined number,e.g., seven, of temporarily consecutive tone-symbols corresponding tothe same tone, the tone-halfslots having a predetermined tone-halfslotindex value k, each tone-symbol within a tone half-slot being identifiedby a relative tone-symbol index j, the equation j=MOD (k+X, 7)identifying tone-symbols within the tone-halfslot which belong to thesubset of tone-symbols, corresponding to the one of the N indicatorvalues, one-tone symbol in each tone-halfslot corresponding to theindicator value being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to 6; where j is aninteger in the range 0 to 6; and k is an integer in the range of 0 tothe total number of tone-halfslots in the segment minus 1, e.g. 0 to111.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., 112tone-halfslots, each tone-halfslot including a predetermined number,e.g., seven, of temporarily consecutive tone-symbols corresponding tothe same tone, the tone-halfslots having a predetermined tone-halfslotindex value k, each tone-symbol within a tone half-slot being identifiedby a relative tone-symbol index j, the equation j=MOD (k−X, 7)identifying tone-symbols within the tone-halfslot which belong to thesubset of tone-symbols, corresponding to the one of the N indicatorvalues, one-tone symbol in each tone-halfslot corresponding to theindicator value being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to 6; where j is aninteger in the range 0 to 6; and k is an integer in the range of 0 tothe total number of tone halfslots in the segment minus 1, e.g., 0 to111.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., ntone-halfslots, each tone-halfslot including a predetermined number,e.g., m, of temporarily consecutive tone-symbols corresponding to thesame tone, the tone-halfslots having a predetermined tone-halfslot indexvalue k, each tone-symbol within a tone half-slot being identified by arelative tone-symbol index j, the equation j=MOD (k+X, m) identifyingtone-symbols within the tone-halfslot which belong to the subset oftone-symbols, corresponding to the one of the N indicator values,one-tone symbol in each tone-halfslot corresponding to the indicatorvalue being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to m−1; where j is aninteger in the range 0 to m−1; and k is an integer in the range of 0 tothe total number of tone halfslots in the segment minus 1, n−1, where nis a positive integer greater than or equal to two and m is a positiveinteger greater than or equal to four. In some such embodiments, m=7.

In some embodiments, a transmission unit is an OFDM tone symbol. In somesuch embodiments, an uplink channel segment, e.g., uplink trafficchannel segment, includes a plurality of tone-halfslots, e.g., ntone-halfslots, each tone-halfslot including a predetermined number,e.g., m, of temporarily consecutive tone-symbols corresponding to thesame tone, the tone-halfslots having a predetermined tone-halfslot indexvalue k, each tone-symbol within a tone half-slot being identified by arelative tone-symbol index j, the equation j=MOD (k−X, m) identifyingtone-symbols within the tone-halfslot which belong to the subset oftone-symbols, corresponding to the one of the N indicator values,one-tone symbol in each tone-halfslot corresponding to the indicatorvalue being communicated, where X is the indicator value beingcommunicated and X is an integer in the range 0 to m−1; where j is aninteger in the range 0 to m−1; and k is an integer in the range of 0 tothe total number of tone halfslots in the segment minus 1, n−1, where nis a positive integer greater than or equal to two and m is a positiveinteger greater than or equal to four. In some such embodiments, m=7.

FIG. 33 is a drawing of an exemplary wireless terminal 3300, e.g.,mobile node, implemented in accordance with the present invention andusing methods of the present invention. Wireless terminal 3300 includesa receiver 3302, a transmitter 3304, a processor 3306, user I/O devices3308, and memory 3310, coupled together via a bus 3312 over which thevarious elements can interchange data and information.

Receiver 3302 is coupled to receive antenna 3303 via which wirelessterminal 3300 can receive downlink signals from base stations includingassignment signals, e.g., assignment signals including assignments ofuplink, e.g., traffic channel, segments including maximum uplink rateoption indicator information. Receiver 3302 includes a decoder 3314 fordecoding received downlink signals.

Transmitter 3304 is coupled to transmit antenna 3305 via which WT 3300can transmit uplink signals, e.g., uplink resource request signals anduplink traffic channel signals using assigned segments, to basestations. In some embodiments, the same antenna is used for both thetransmitter 3304 and receiver 3302. Transmitter 3304 includes an encodermodule 3316, a modulator module 3318, a rate option indicator module3320, and a transmission module 3322.

Encoder module 3316 generates coded bits at a coding rate correspondingto an uplink rate option, the coded bits being generated from data bitsto be transmitted. Modulator module 3318 modulates the coded bits intomodulation symbols using a modulation method corresponding to the uplinkrate option. For example, the WT 3300 may have selected to use aparticular uplink data rate option for an uplink traffic channel segmentassigned to the WT, and the selected data rate option corresponds to acoding rate and a modulation method. The corresponding coding rateinformation is used by the encoder module 3316 to perform encoding,e.g., block encoding for the segment, of a set of data bits, sometimesreferred to as information bits, to a set of coded bits. Thecorresponding modulation method, e.g., QPSK or QAM16, determines theconstellation used for mapping the coded bits output from encoder module3316 into modulation symbol values by modulator module 3318.

Rate option indicator module 3320 generates, on a per uplinktransmission segment basis, an indication of the uplink rate option usedfor encoding of data corresponding to the uplink transmission segment.In some embodiments, rate option indicator module 3320 includes one ofthe following modules: scaling module 3324 and coded bit module 3326.Scaling module 3324 scales, for a given uplink traffic channel segment,at least some of the modulation symbols output from modulation module3318, as a function of a determined rate option indicator valuecorresponding to the uplink traffic channel segment, to produce anenergy pattern within the segment, the energy pattern communicating theindicator value. Coded bit module 3326 generates the indication of theuplink rate option by including coded bits, indicating the rate optionindicator value, which are transmitted as symbol constellation valueswithin the uplink traffic channel segment.

Transmission module 3322, e.g., a power amplifier output stage oftransmitter 3304, transmits transmission modulation symbols conveyingboth the data bits and an indicator of the uplink rate optioncorresponding to the transmission segment. For example, in an embodimentusing scaling module 3324, the transmission modulation symbols maycorrespond to the output modulation symbols from modulation module 3318,but with a subset of the output modulation symbols from the modulationmodule 3318 having been rescaled by module 3324. In some embodimentsusing coded bit module 3326, the transmission modulation symbols may bepartitioned into those conveying the coded indicator bits and thoseconveying the coded indicator bits. In other embodiments using coded bitmodule 3326, at least some of the transmission modulation symbols mayconvey both coded data bits and coded indicator bits.

User I/O devices 3308, e.g., display, speaker, microphone, camera,keypad, keyboard, mouse, control switches, etc., allow the user of WT3300 to input data/information, output data/information, and controlfunctions, e.g., power on, initiate a call, etc.

Memory 3310 includes routines 3328 and data/information 3330. Theprocessor 3306, e.g., a CPU, executes the routines 3328 and uses thedata/information 3330 in memory 3310 to control the operation of the WT3300 and implement the methods of the present invention. Routines 3328include a communications routines 3332 and WT control routines 3334. Thecommunications routines 3332 implement the communications protocolsimplemented by the WT 3300. WT control routines 3334 include a receivercontrol module 3336, a transmitter control module 3338, a user interfacecontrol module 3340, and an indicator value determination module 3342.Receiver control module 3336 controls operation of receiver 3302;transmitter control module controls operation of transmitter 3304, userinterface control module 3340 controls operation of user I/O devices3308.

Indicator value determination module 3342 determines, e.g., for a givenuplink traffic channel segment assigned to the WT, an indicator valuefrom a maximum rate option value and a selected rate option. Thedetermined indicator value is used by the rate option indicator module3320 to generate the indication of the uplink rate option. Indicatorvalue determination module 3342 includes mapping module 3344. Mappingmodule 3344 maps the selected rate option, corresponding to an uplinktraffic channel segment assigned to WT 3300, to an indicator value,using a first function when the received maximum rate option valuecorresponding to the segment is in a first set of values and using asecond function, which is different from the first function, when thereceived maximum rate option value is in a second set of values, thesecond set of values being different from the first set of values.

Data/information 3330 includes WT data/information 3331, uplink resourcerequest messages 3333, received uplink segment assignment messages 3335,and system data/information 3337. WT data/information 3331 includes userdata 3339, base station identification information 3348, WTidentification information 3341, device/session/resource information3350, and uplink assigned segment information (UL assigned segment 1information 3352, . . . , UL assigned segment N information 3353). Userdata 3339, e.g., voice data, video data, text data, file data, etc.,includes data pertaining to communications sessions with a peer nodes ofWT 3300. WT identification information 3341 includes a base stationassigned WT user identifier, e.g., an active user identifier. Basestation identification information 3348 includes an identifierassociated with the base station which WT 3300 is currently using as itspoint of network attachment. Device/session/resource information 3350includes, e.g., device control information, ongoing session informationsuch as information identifying the peer node, routing information,etc., and assignment segment information including informationidentifying uplink and downlink traffic channel segments assigned to theWT 3300 by the base station.

Uplink assigned segment 1 information 3352 includes uplink assignmenttype information 3354, uplink segment identification information 3356,received maximum allowed uplink data rate information 3358, selecteduplink data transmit rate information 3360, indicator value 3362, userdata bits 3364, coded bits 3366, modulation symbol values 3368,transmission modulation symbol values 3370. Uplink assignment typeinformation 3354 includes information identifying the type of assignmentcorresponding to the uplink segment, e.g., a regular assignment or aflash assignment. In some embodiments, a mapping function or functionsmay also depend upon the type of assignment. Uplink segmentidentification information 3356 includes information identifying theuplink segment, e.g., via an index value. For example, the uplink timingand frequency structure may include a fixed number of indexed uplinktraffic channel segments, and the set of indexed uplink segments mayrepeat. Received maximum allowed uplink data rate 3358 includes a basestation communicated maximum uplink rate option indicator value.Selected uplink data transmit rate 3360 includes a WT selected uplinkdata rate option to be used for the uplink traffic channel segment,e.g., corresponding to number of data bits or frames of data bits to becommunicated in the uplink traffic channel segment. The selected uplinkrate option is less than or equal to the received maximum allowed uplinkrate option. In some embodiments, for some segments, in the selectionprocess of the WT uplink rate option for an uplink traffic channelsegment, the maximum uplink rate option is further reduced from the BSvalue based on interference information determined at the WT, e.g., abeacon ratio report, and then the selection is performed by the WT,e.g., based on the amount of information to be communicated and/orurgency of the information.

Indicator value 3362 is the output of indicator value determinationmodule 3342 and is used by rate option indicator module 3320 toincorporate the value into the uplink traffic channel segment signals.In some embodiments, the indicator value is one of N possible indicatorvalues, each of the N possible indicator values corresponding to adifferent subset of transmission units in the uplink traffic channelsegment, each transmission unit corresponding to one of said modulationsymbols to be communicated in the segment, the indicator value beingcommunicated by the scaling module 3324 applying a higher power scalefactor to the modulation symbols corresponding to the subset oftransmission units in the segment corresponding to the indicator valueto be communicated, where N is a positive integer greater than 1. Insome embodiments, each of the N different subsets of transmission unitsare non-overlapping with each transmission unit corresponding to at mostone of the N different subsets. In some such embodiments, all thetransmission units are included in a set of subsets which is formed fromthe combination of the N different subsets of transmission units.

User data bits 3364 are bits of user information, e.g., representingvoice, video, text, files, etc., corresponding to the segment, to beinput to encoder module 3316, while coded bits 3366 represents theoutput bits of the encoder module 3316. The coded bits 3366 are mappedonto modulation symbol values 3368 by the modulation module 3318. Thetransmission module symbol values 3370 are the symbol values transmittedby transmission module 3322 and correspond to the modulation symbolvalues, e.g., with some of the modulation symbol values 3368 having beenrescaled by the scaling module 3324 to generate an energy pattern forthe segment conveying the indicator value 3362.

UL resource request messages 3333 includes requests for uplink trafficchannel air link resources, e.g., requests for segments and/or requestsidentifying the amount of user data bits to be communicated via theuplink, e.g., a number of frames. Received uplink segment assignmentmessage 3335 includes received information identifying the WT to whichthe corresponding uplink segment is assigned and a maximum rate optionindicator value.

System data/information 3337 includes uplink/downlink timing andfrequency structure information 3372, BS identification information3378, first mapping function information 3380, second mapping functioninformation 3382, uplink data rate used information 3383, scalinginformation 3385, 1^(st) set of max rate values 3386, 2^(nd) set of maxrate values 3387, and indicator information 3384. Uplink/downlink timingand frequency structure information 3372 includes, e.g., carrierfrequencies used, tones used, tone blocks used, tone hopping sequencesused, transmission unit information, e.g., OFDM tone-symbol information,OFDM symbol transmission timing information, grouping of OFDM symbolsinto half-slots, slots, superslots, beaconslots, etc. ULIDL timing andfrequency structure information 3372 includes segment information 3374,e.g., information identifying indexed uplink traffic channel segments inthe structure. Segment information 3374 includes half-slot information3376, e.g., information identifying indexing of tone-halfslots within anuplink traffic channel segment and information identifying indexedtone-symbols within the tone-halfslots. Base station identificationinformation 3378 includes information identifying different basestations within the wireless communications system which may be used byWT 3300 as its point of attachment, e.g., beacon information, pilot toneinformation, hopping pattern information, carrier information, etc.,associated with each particular base station. First mapping functioninformation 3380 includes information used by mapping module 3344 to mapa selected UL rate option to an indicator value, when the received maxrate option value is in the 1^(st) set of rate values. Second mappingfunction information 3382 includes information used by mapping module3344 to map a selected UL rate option to an indicator value, when thereceived max rate option value is in the 2^(nd) set of rate values.Scaling information 3385 is used by scaling module 3324 to determine theamount to rescale the selected modulation symbol values in order togenerate an energy pattern in the uplink traffic channel segment whichconveys the indicator value. The possibilities of maximum rate indicatorvalues that may be communicated from the base station may be partitionedinto a 1^(st) set of maximum rate values 3386 and a second set ofmaximum rate values 3387, each set corresponding to a mapping function3380, 3382, respectively. For example, in a WT supporting eight uplinkrate options, but with the indicator value being limited to sevendifferent value possibilities, an exemplary first set of maximum ratevalues 3386 may be the set of values {0, 1, 2, 3, 4, 5, 6} while anexemplary second set of maximum rate values may be the set {7}. The basestation, having communicated the maximum rate value for the uplinksegment in its assignment message knows which mapping function was usedby the WT to generate the indicator and thus is able to properlyinterpret the indicator and associate the indicator with the uplink datarate option being used by the WT.

Uplink data rate used information 3383 includes a plurality of sets ofinformation corresponding to the different uplink data rate optionssupported by the WT (data rate 1 information 3388, data rate Minformation 3389). Data rate 1 information 3388 includes codinginformation 3390, e.g., identifying a coding rate, and modulationinformation 3391, e.g., identifying a modulation method with amodulation constellation, e.g., QPSK or QAM 16. In some embodiments, theWT supports more data rate options than can be indicated by the numberof possible indicator values. For example, the indicator value can beone of N possible values, the total number of rate options supported bythe wireless terminal can be M, M and N are positive values greater than1, and M>N. For example, N can be equal to 7 and M can be equal to 8.

Indicator information 3384 includes a plurality of sets of indicatorinformation (indicator 1 information 3392, . . . , indicator Ninformation 3393), each associated with a different indicator value.Indicator 1 information 3394 includes one of energy pattern information3394 and coded bit information 3395. The coded bit information 3395includes mapping information associating the indicator value with apattern of coded bits to be transmitted as symbol constellation values.

Energy pattern information 3394 includes information used in generatingthe energy pattern within the segment corresponding to the indicatorvalue. For example, the uplink transmission segment includes a pluralityof tone-halfslots, each tone-halfslot including a predetermined numberof temporally consecutive tone-symbols corresponding to the same tone,the tone-halfslots having a predetermined tone-halfslot index orderwithin the segment, each tone half-slot being identified by atone-halfslot index value k, each tone-symbol within a tone-halfslotbeing identified by a relative tone-symbol index j, the equation j=MOD(k+X, m) identifying tone-symbols within the tone-halfslots which belongto the subset of tone-symbols, corresponding to the one of the Nindicator values, one tone-symbol in each tone-halfslot corresponding tothe indicator value being communicated, where X is the indicator valuebeing communicated and X is an integer in the range 0 to m−1; where j isan integer value in the range 0 to m−1; k is an integer value in therange of 0 to the total number of tone-halfslots in the segment minus 1,and m is greater than 4. In some embodiments m=7.

FIG. 34 comprising the combination of FIG. 34A and FIG. 34B is aflowchart 3400 of an exemplary method of operating a wireless terminalin accordance with the present invention. The exemplary wirelessterminal, e.g., a mobile node, implemented in accordance with thepresent invention, may be, e.g., part of a wireless spread spectrum OFDMcommunications system including at least one base station and aplurality of wireless terminals. In some embodiments, the wirelesscommunications system includes a plurality of base stations, and the WTregisters with the base station in whose cell it is currently located.The base station or stations transmit downlink assignment informationfor uplink traffic channel segments, the assignment information for anuplink traffic channel segment including a maximum rate optionindicator. In some embodiments, the maximum rate option indicator may becommunicated as part of an OFDM signal. For at least some of the uplinktraffic channel segment assignments assigned to the WT, the WT selectsthe uplink rate option to use for the corresponding uplink trafficchannel segment, the selected rate option being less than or equal to anmaximum uplink rate option. Each uplink rate option may correspond to acoding rate and modulation scheme. For example, the table of FIG. 23lists 8 uplink rate options that may be supported by a WT in anexemplary system.

The method of operation starts in start step 3402, where the WT ispowered on. Operation proceeds to step 3404, where the WT storesinformation indicating a mapping between each of a plurality of rateoptions and an encoding method, at least two of the plurality of rateoptions corresponding to coding different numbers of information bits inan assigned uplink traffic channel segment. Operation proceeds from step3404 to step 3406, where the WT stores information between each of aplurality of rate options and a modulation method. In some embodimentsat least 8 different maximum rate options can be indicated. In someembodiments, at least two of the plurality of rate options correspondsto different modulation methods, e.g., QPSK and QAM16. In someembodiments, step 3406 includes sub-step 3408. In sub-step 3408, the WTstores modulation information indicating that QPSK modulation should beused when transmitting data in an uplink traffic channel segment forwhich the lowest rate option is indicated. In some embodiments, steps3404 and step 3406 are performed as part of a WT softwareload/initialization process, e.g., downloading mapping information intoa non-volatile memory for future use by the WT. In some such embodiment,steps 3404 and 3406 need not be repeated during subsequent turn-onsprovided the stored mapping information does not change. Operationproceeds from step 3406 to step 3410.

In step 3410, the WT is operated to receive an uplink traffic channelsegment assignment of a corresponding uplink traffic channel segment anda maximum uplink rate option indicator, said maximum uplink rate optionindicator indicating a value which can be used to determine an indicatedmaximum uplink rate option. In some embodiments, for at least some typesof uplink traffic channel assignments, e.g., regular uplink trafficchannel assignments, the maximum rate option indicator is a 3 bitindicator and the WT includes information associating each of the 8values which can be indicated with information indicating differentnumbers of information bits to be coded into the segment. In someembodiments, for at least some types of uplink traffic channelassignments, e.g., flash uplink traffic channel assignments, the maximumrate option indicator is communicated in the received signal using fewerbits than the number of bits required to uniquely identify each of theselectable uplink rate options, e.g., one bit is used for the maximumuplink rate option indicator and the WT supports more than twoselectable uplink rate options. In some embodiments, the WT supportsfirst and second signaling methods for communicating maximum rate optionindicators, and the maximum rate option indicator includes one bit if itwas communicated using a first signaling method and 3 bits if it wascommunicated using a second signaling method. For example, the firstsignaling method may use conventional coherent modulation techniquesusing QPSK with per tone average transmission power for non-zeromodulation symbol values at a first level, while the second signalingmethod may use non-coherent modulation techniques including some zeroand some non-zero QPSK modulation symbols values assigned to allocatedresources, with the non-zero QPSK modulation symbol values beingtransmitted at a second level, wherein the second level is higher thanthe first level. Operation proceeds from step 3410 to step 3412.

In step 3412, the WT determines as to whether or not the received uplinktraffic channel segment assignment was intended for the WT or foranother WT. For example, the WT, having previously registered with theBS which transmitted the assignment may have been previously assigned aWT identifier by the BS, the assignment signal may include a WTidentifier to associate the assignment with a particular registered WT,and the WT may compare the WT identifier in the received assignment withits own BS assigned WT identifier to determine whether it is theintended recipient of the assignment. If the received assignment of step3410 was not for the WT, operation proceeds from step 3412 to step 3410,where in step 3410 the WT continues to receive additional assignments.If the received assignment was for the WT operation proceeds from step3412 to step 3414, where the WT performs operations related to theassignment and back to step 3410, where the WT receives additionaluplink traffic channel assignments. The WT can receive multiple uplinktraffic channel assignments from the same BS intended for the WT, e.g.,with different uplink traffic channel assignments corresponding todifferent uplink traffic channel segments and with each assignmentincluding a maximum uplink rate option indicator. In some embodiments,some assignment messages, e.g., some regular assignment channelmessages, may include multiple, e.g., two, uplink traffic channelassignments, and one or more of those assignments may be directed to theWT.

In step 3414, the WT determines the indicated maximum uplink rate optionfrom the value included in the maximum uplink rate option indicator andadditional information known to the wireless terminal. In someembodiments, the additional information is information indicatingwhether the maximum uplink rate option indicator was received in a firstor second assignment channel, e.g., a regular assignment channel or aflash assignment channel. In some embodiments, when the maximum uplinkrate option information was received in a second assignment channel, theadditional information further includes signal interference information,e.g., beacon ratio report information. For example, a single bit valuecommunicated in a received second assignment channel may distinguishbetween two maximum uplink rates, e.g., rate option 3 or rate option 7,and then generic beacon ratio report results, based on WT measurements,can be used to further qualify, e.g., reduce, the maximum WT uplink rateoption allowed. Operation proceeds from step 3414 via connecting node A3416 to step 3418.

In step 3418, the wireless terminal determines if the indicated maximumuplink rate option corresponds to a single predetermined rate option,e.g., the lowest rate option. If the WT determines that the indicatedrate option corresponds to a single predetermined rate option, thenoperation proceeds from step 3418 to step 3420; otherwise, operationproceeds from step 3418 to step 3422.

In step 3420, the WT transmits data in the traffic channel segmentcorresponding to the received assignment segment in accordance with thesingle predetermined rate option, e.g., the lowest uplink rate optionsupported by the WT. In some embodiments, the single predetermined rateoption corresponds to the lowest traffic channel coding rate optionwhich can be indicated by the maximum uplink rate option indicator,e.g., uplink traffic channel rate option 0 which codes 224 informationbits into a codeword of 1344 coded bits and represents a coding rate of1/6.

In step 3422, the WT selects one of the plurality of rate options from aplurality of predetermined rate options corresponding to the indicatedmaximum uplink rate option. In some embodiments, the selection of step3422 may be based upon how much information the WT needs to communicateand/or the time urgency of the communication. Operation proceeds fromstep 3422 to step 3424. In step 3424, the WT transmits data in thetraffic channel segment corresponding to the received assignment segmentin accordance with the selected one of the plurality of rate optionscorresponding to the indicated maximum uplink rate option.

FIG. 35 is a drawing of an exemplary wireless terminal 3500, e.g., amobile node, implemented in accordance with the present invention andusing methods of the present invention. Exemplary WT 3500 includes areceiver 3502, a transmitter 3504, a processor 3506, user I/O devices3508, and memory 3510 coupled together via a bus 3512 via which thevarious elements can interchange data and information. Receiver 3502 iscoupled to a receive antenna 3503 via which the WT 3500 can receivedownlink signals, e.g., downlink OFDM signals, from base stations, thereceived downlink signals including assignments of uplink trafficchannel segments and corresponding maximum uplink rate optionindicators. Receiver 3502 includes a decoder 3514 for decoding receivedsignals and an assignment processing module 3516. The assignmentprocessing module 3516 processes the one or more received trafficchannel assignments from a base station indicating assignment of uplinktraffic channels to WT 3500. In some embodiments, an uplink trafficchannel assignment message includes a maximum uplink rate optionindicator, which is processed by module 3516.

Transmitter 3504 is coupled to a transmit antenna 3505 via which the WT3500 transmits uplink traffic channel signals including uplink trafficchannel segment signals, e.g., uplink OFDM traffic channel segmentsignals, to base stations. In some embodiments, the same antenna is usedfor both receiver 3502 and transmitter 3504. Transmitter 3504 includesan encoder 3518 and a modulation module 3520. For a given uplink trafficchannel segment, the rate option being used, e.g., selected, by WT 3500,corresponds to a coding rate and modulation method. Encoder 3518, e.g.,a block encoder such as an LDPC encoder, utilizes the coding rate forthe segment and codes user data bits into coded data bits. Modulationmodule 3520 utilizes the modulation method, e.g., identifying amodulation constellation, for the segment and maps the coded bits fromthe output of the encoder 3518 to modulation symbol values.

User I/O devices 3508, e.g., display, keyboard, keypad, mouse, speaker,microphone, camera, control switches, etc., allows the user of WT 3500to input user data/info intended for peer nodes and to output userdata/info from peer nodes. In addition, user I/O devices 3508 allow theuser to control operations of WT 3500, e.g., initiating a call, poweringdown, etc.

Memory 3510 includes routines 3522 and data/information 3524. Theprocessor 3506, e.g., a CPU, executes the routines 3522 and uses thedata/information 3524 in memory 3510 to control the operation of the WT3500 and implement methods of the present invention.

Routines 3522 includes communications routines 3526, which implementsthe communication protocols used by the WT 3500, and WT control routines3528. WT control routines 3528 includes a receiver control module 3530,a transmitter control module 3532, a user interface control module 3534,a maximum uplink rate option determination module 3536, and an uplinkrate option selection module 3538. Receiver control module 3530 controlsoperations of receiver 3502; transmitter control module 3532 controlsoperations of transmitter 3504; user interface control module controlsoperations of user I/O devices 3508. Transmitter control module 3532includes a traffic channel segment transmission control module 3540.Traffic channel segment transmission control module 3540, operating inconjunction with transmitter 3504, enables the transmission of uplinksignals in uplink traffic channel segments corresponding to receivedassignments, in accordance with the uplink rate option the WT is usingfor each of the assigned uplink traffic channel segments. For someuplink traffic channel segments, the WT may have received a maximumuplink rate option indicator allowing the WT to select between aplurality of different rate options. For some uplink traffic channelsegments, the WT may have received a maximum uplink rate optionindicator that corresponds to a single predetermined rate option thatthe WT uses. For example, the single predetermined rate option maycorrespond to the lowest traffic channel uplink rate option which can beindicated by the maximum uplink rate option indicator. In someembodiments the single predetermined rate option may correspond to thelowest coding rate supported by the WT for uplink traffic channelsegments and QPSK modulation.

Maximum uplink rate option determination module 3536, which is coupledto receiver 3502, determines the indicated maximum uplink rate optionfrom the value included in the maximum uplink rate option indicator andadditional information known to the WT 3500. For example, the additionalinformation may be information indicating whether the maximum uplinkrate option information was received in a first or second assignmentsignal channel. In some embodiments, a first assignment signal channelmay be a regular assignment signal channel using coherent modulationsignaling while a second assignment signal channel may be a flashassignment channel using non-coherent modulation signaling. In someembodiments, the additional information includes stored signalinterference information. For example, for some segments, the receivedmaximum uplink rate option indicator may limit, e.g., cap, the uplinkrate options that the WT may select, and interference informationmeasurements by the WT may be used to further limit, e.g., cap, the rateoptions that the WT may select.

Uplink rate option selection module 3538, for at least some uplinktraffic channel segments, selects, the one of the plurality of rateoptions from a plurality of predetermined rate options corresponding tothe indicated maximum uplink rate option, to be used subsequently intransmitting data in the assigned uplink traffic channel segment inaccordance with the selected one of a plurality of rate options. Forexample, consider that the WT supports 8 uplink rate option (0, . . .7), that the assignment is received via a regular assignment channel,that the received assignment includes a maximum rate indicator whichindicates the maximum allowed uplink rate option for the assigned uplinktraffic channel segment is 5, and that the WT determines that itscurrent uplink data transmission requirements could be satisfied byusing rate option 3. In such an exemplary case, the selection module3538 may select to use uplink rate option 3 from a potential set ofallowable rate option {0, 1, 2, 3, 4, 5}. The selected uplink rateoption 3 corresponds to coding rate information and modulationinformation, which is utilized by transmitter 3504.

Data/information 3524 includes WT data/information 3542, uplink resourcerequest messages 3544, received uplink segment assignment messages 3546,and system data/information 3550. In some embodiments, data/info 3524includes a received maximum uplink rate option indicator 3548, e.g., therate option indicator is communicated outside of the uplink segmentassignment message, e.g., as a separate message or incorporated in amessage with other control information.

WT data/information 3542 includes user data 3552, e.g., voice, video,text, files, etc., WT identification information 3554, e.g., a basestation assigned WT identifier, base station identification information3556, e.g., information identifying the BS being used currently by WT3550 as its point of network attachment, device/session/resourceinformation 3558, signal interference information 3560, and sets ofuplink assigned segment information (UL assigned segment 1 information3562, UL assigned segment N information 3564). Device session/resourceinformation 3558 includes, e.g., information identifying ongoingcommunications sessions, peer nodes, routing information, uplink anddownlink channel segments assigned to WT 3500, etc. Signal interferenceinformation 3560 includes, e.g., beacon ratio report information. Insome embodiments, for some types of uplink assignment signals, e.g.,uplink assignment signals associated with a flash assignment channel,the signal interference information 3560 may be use to further limit themaximum allowable uplink data rate option that may be selected by the WTfor an uplink traffic channel segment.

Uplink assigned segment 1 information 3562 includes uplink assignmentchannel information 3566, uplink segment identification information3568, received maximum uplink rate option indicator 3570, a maximumallowed uplink rate option 3571, a selected uplink data rate option3572, user data bits 3574, coded bits 3576, and modulation symbol values3578. Uplink assignment channel information 3562 includes informationindicating whether the maximum uplink rate option indicator was receivedin a first of second assignment channel, e.g., a regular or flashassignment channel. Uplink segment identification information 3568includes, e.g., a segment index number identifying the segment within arepetitive uplink timing and frequency structure including a fixednumber of indexed uplink traffic channel segments. Received maximumuplink rate option indicator 3570 includes information indicating themaximum uplink rate option that may be used by the WT from theperspective of the BS. Maximum allowed uplink rate option 3571 is themaximum rate option that may be used by the WT for the uplink segmenttaking into consideration the base stations input, and, in someembodiments, for some types of assignments, additionally taking intoconsideration signal interference information 3560. Selected UL datarate option 3572 is the output of module 3538 and is a data rate optionless than or equal to the data rate option indicated by maximum alloweduplink rate option 3571. User data bits 3574, e.g., user bitsrepresenting voice, video, text, files, etc., are input for a codingblock for the uplink traffic channel segment, while coded bits 3576 areoutput for the coding block, with the coding being performed by encoder3518, using the coding rate that is mapped to correspond to the selecteddata rate option 3572 for the segment. Modulation symbol values 3578 arethe modulation symbol values corresponding to when the coded bits 3576are mapped to modulation symbols of the modulation constellation used bythe modulation method for the segment, the modulation method having beenmapped to correspond to the selected data rate option 3572.

Uplink resource request messages 3544 are messages to be communicatedvia uplink signaling to a base station requesting uplink traffic channelsegments, and/or identifying amounts of uplink data to be communicatedby the WT 3500. Received uplink segment assignment messages 3546 conveyuplink segment assignment information. In some embodiment, someassignment messages include one or a plurality of uplink assignments. Insome embodiments, some assignment messages include at most one uplinkassignment. For example a regular traffic channel assignment message mayinclude one or two uplink traffic channel segment assignments, while aflash assignment channel message may include at most one uplink trafficchannel segment assignment. In some embodiments, a received uplinksegment assignment message 3546 includes a maximum uplink rate optionindicator or indicators 3580, with each indicator corresponding to anassigned uplink segment of the message.

System data/information 3550 includes uplink/downlink timing andfrequency structure information 3582, uplink data rate used information3584, base station identification information 3586, indicated maximumuplink rate option/predetermined rate option correspondence information3588, indicated maximum uplink rate option decoding information 3590,and rate option selection criteria 3591. Uplink data rate usedinformation 3584 includes a plurality of sets of rate option information(rate 1 option information 3594, . . . , rate M option information3598). Coding information and modulation information is mapped tocorrespond to each of the rate options supported by the WT 3500. Rate 1option information 3594 includes coding rate information 3594 andmodulation information 3596. For example coding rate informationspecifies a number of data bits or frames of data bits, a correspondingnumber of coded bits obtained, and a cod used, while modulationinformation 3596 identifies a modulation method, e.g., QPSK or QAM 16with its associated modulation constellation. At least two of theplurality of uplink rate options correspond to coding different numbersof information bits for a given uplink traffic channel segment that maybe assigned to WT 3500. At least two of the plurality of uplink rateoptions correspond to different modulation methods, e.g., QPSK and QAM16.

Information 3588 includes information linking maximum uplink rate optioninformation with predetermined sets of rate options, e.g., mappingtables or mapping information associating rate option indicator typesand/or values with uplink rate options. In some embodiments,correspondence information 3588 may also include information identifyingcriteria, e.g., signal interference information criteria used to furtherrestrict the received indicated maximum uplink rate option. Indicatedmaximum uplink rate option decoding information 3590 includesinformation identifying types of assignment signals with number of bits,e.g., in a field conveying the maximum uplink rate option indicator, andwith a modulation method used to convey the assignment signal. Forexample a flash type assignment channel signal may use a one bit fieldto convey the maximum rate option indicator and may use a non-coherentmodulation scheme, while a regular type assignment channel signal mayuse a three bit field to convey the maximum rate option indicator andmay use a coherent modulation scheme. The flash assignment channelmaximum rate option indicator uses fewer bits than the number of bitsrequired to signal to uniquely identify each of the selectable uplinkrate options, e.g., one bit is used for the flash maximum rate optionindicator, but three bits would be required to uniquely indicate each ofthe eight uplink rate options supported by the WT. In some embodiments,the WT supports eight uplink data rate options and a first type ofassignment can encode a maximum uplink rate option indicator which mayconvey any of the eight possibilities, while a second type of assignmentencodes two possibilities. In some such embodiments, if the assignmentsignal is of the first type and conveys a maximum rate option indicatorindicating the lowest rate, the wireless terminal is effectivelyassigned to use to lowest rate by the base station for that particularuplink traffic channel segment.

In some embodiments, where the maximum rate option indicator is a 3 bitindicator, the WT includes stored information associating each of the 8values which can be indicated with information indicating differentnumbers of information bits to be coded in the segment. For example, theuplink data rate used info 3584 can include 8 sets of information, eachset corresponding to a different number of information bits, e.g., userdata bits, to be coded for the segment.

Rate option selection criteria 3591 is used by the uplink rate optionselection module 3538 to determine the rate option to use less than orequal to the maximum allowed uplink rate option, where the maximumallowed uplink rate option indicates a rate option higher than thelowest rate option supported by the WT 3500. For example, rate optionselection criteria 3591 may include criteria based on amounts of uplinkdata to be communicated, data transmission time urgency information,and/or a service tier level.

FIG. 36 is a flowchart 3600 illustrating an exemplary method, inaccordance with the present invention, of operating a base station in acommunications system to generate and transmit assignment informationindicating the assignment of uplink communications segments, each uplinkcommunications segment having a predetermined duration. For example, thebase station may be a base station in an exemplary OFDM spread spectrumwireless communications system using a plurality of different typesuplink traffic channel segments. For example the exemplary system mayhave an uplink traffic channel using three different types of uplinktraffic channel segments: a first type of uplink traffic channel segmentusing 7 tones for a duration of 112 OFDM symbol transmission timeintervals, a second type of uplink traffic channel segment using 14tones for 56 OFDM symbol transmission time intervals, a third type ofuplink traffic channel segment using 28 tones for a duration of 28 OFDMsymbol transmission time intervals. Operation starts in step 3602, wherethe exemplary base station is powered on and initialized, and proceedsto either step 3604 or step 3606.

In some embodiments, the base station uses information from first andsecond maximum rate option indicator tables, and step 3604 is performed,e.g., during an initialization process of the base station, where thebase station stores first and second maximum rate option indicatortables. In some such embodiments, step 3604 is performed once, e.g.,when the base station is being configured; while in some other suchembodiments, step 3604 is performed once during each turn-on orre-initialization of the base station, e.g., where maximum rate optioninformation is transferred from non-volatile memory into first andsecond maximum rate option indicator tables in volatile memory. In otherembodiments, maximum rate option indicator tables may not be used, e.g.,maximum rate option information corresponding to information included infirst and second rate option indicator tables can be embedded in aroutine or routines.

In step 3606, the base station is controlled to start operating the basestation on a predetermined timing/frequency structure, e.g., accordingto a periodic transmission schedule having a fixed timing relationshipbetween the transmission of assignments and the uplink traffic channelsegments being assigned. For example, the base may operate using anuplink timing/frequency structure including an indexed set of uplinktraffic channel segments, which repeat on a periodic basis, with each ofthe indexed uplink traffic channel segments being associated with aparticular assignment in the downlink timing and frequency structure.For example, the uplink timing/frequency structure may include a set ofseventy-seven indexed (0 . . . 76) uplink traffic channel segments, 28of which are associated with first type assignments and 49 of which areassociated with second type assignments.

Operation proceeds from step 3606 to step 3608. Step 3608 is performedand operational processing further directed for each uplink trafficchannel assignment, depending upon the result of step 3608. In step3608, it is determined whether the assignment is a first type assignmentor a second type assignment. For example, first type assignments may bedesignated as flash type assignments and second type assignments may bedesignated as regular type assignments; the set of indexed uplinktraffic channel segments may be partitioned such that some areassociated with first type assignments and some are associated withsecond assignments. If an assignment is a first type assignmentoperation proceeds to step 3610, while if an assignment is a second typeassignment operation proceeds to step 3612.

In step 3610, the base station is operated to select a first typemaximum rate option indicator value, said value being selected from aset of values including at least one value corresponding to the highestrate option supported by the system and another value corresponding toan intermediate rate option supported by the base station. For examplean exemplary system may support 8 uplink data rate options (0, 1, 2, 3,4, 5, 6, 7) for uplink traffic channel segments, with rate option 0representing the lowest data rate option and rate option 7 representingthe highest data rate option, and the first type maximum rate optionindicator may be designated as a congestion indicator. The congestionindicator may use one information bit to convey either a value of 1corresponding to maximum WT uplink data rate option 7 or a value of 0corresponding to a maximum WT uplink data rate option 3, and the basestation may select between the two possibilities. For example, the basestation may, for a given first type assignment, select, e.g., a value of0 corresponding to maximum WT uplink data rate option 3. In someembodiments, step 3610 includes sub-step 3614, where the base stationuses the first maximum uplink rate option table. Operation proceeds fromstep 3610 to step 3616.

In step 3616, the base station transmits over a wireless communicationschannel a first assignment including the first maximum uplink rateoption indicator value indicating the first maximum uplink rate optionto be used by a wireless terminal to which the first assignment isdirected in determining the actual uplink transmission rate to be usedwhen the wireless terminal is transmitting in a first communicationssegment. The first communications segment is the uplink traffic channelsegment corresponding to the first assignment, the first assignmentbeing a first type assignment, e.g., a flash assignment. For example,the base station may transmit an assignment corresponding to uplinktraffic channel segment with index number=3, the assignment including aWT identifier field of 5 bits, and a congestion indicator field of 1bit. The WT identifier field may include a BS assigned WT ON stateidentifier, identifying the WT to which the assignment is directed fromamong the plurality of WTs currently registered with the BS and in theON state of operation. The congestion indicator may be, e.g., a value of0 indicating that the maximum uplink data rate option that the WT mayuse for the corresponding uplink traffic channel segment is data rateoption 3. The WT receiving the assignment, in some embodiments, usesadditional criteria, in further limiting the maximum uplink data rate touse, e.g., generic beacon ratio report information.

Step 3616 includes sub-step 3618. In step 3618, the base station uses afirst type modulation method for conveying the first type selected maxuplink rate indicator value. For example, the first type selected maxuplink rate indicator value may be part of information conveyed in aflash downlink control sub-channel segment used for assigning uplinktraffic channel segments, and flash modulation signaling techniques maybe used. The flash modulation signaling techniques may use anon-coherent modulation scheme.

Returning to step 3612, in step 3612, the base station is operated toselect a second type maximum rate option indicator value, said secondtype maximum rate option indicator including more bits than said firsttype maximum rate option indicator allowing for more maximum uplink rateoptions to be specified than can be indicated using the first typeindicator. For example, consider the exemplary system, described withrespect to step 3610 supporting 8 uplink data rate options (0, 1, 2, 3,4, 5, 6, 7) for uplink traffic channel segments, with rate option 0representing the lowest data rate option and rate option 7 representingthe highest data rate option, and consider that second type maximum rateoption indicator may be designated as a rate option in the assignment.The rate option may use three information bit to convey either a valueof (0, 1, 2, 3, 4, 5, 6, 7) corresponding to maximum WT uplink data rateoption (0, 1, 2, 3, 4, 5, 6, 7), respectively, and the base station mayselect between the eight possibilities. For example, the base stationmay, for a given second type assignment, select, e.g., a value of 5corresponding to maximum uplink data rate option 5. In some embodiments,step 3612 includes sub-step 3620, where the base station uses the secondmaximum uplink rate option table. Operation proceeds from step 3612 tostep 3622.

In step 3622, the base station transmits over a wireless communicationschannel a second assignment including the second maximum uplink rateoption indicator value indicating the second maximum uplink rate optionto be used by a wireless terminal to which the second assignment isdirected in determining the actual uplink transmission rate to be usedwhen the wireless terminal is transmitting in a second communicationssegment. The second communications segment is the uplink traffic channelsegment corresponding to the second assignment, the second assignmentbeing a second type assignment, e.g., a regular assignment. For example,the base station may transmit an assignment corresponding to uplinktraffic channel segment with index number=9, the assignment including aWT identifier field of 5 bits, and a rate option field of 3 bits. The WTidentifier field may include a BS assigned WT ON state identifier,identifying the WT to which the assignment is directed from among theplurality of WTs currently registered with the BS and in the ON state ofoperation. The WT to which the second communications segment is assignedmay be the same or a different WT than the WT to which the firstcommunications segment was assigned as referred to in step 3616. Therate option may be, e.g., a value of 5 indicating that the maximumuplink data rate option that the WT may use for corresponding uplinktraffic channel segment is data rate option 5.

In some embodiments, step 3622 includes sub-step 3624. In sub-step 3624,the base station uses a second type modulation method for conveying thesecond type selected max uplink rate indicator value. For example thesecond type selected max uplink rate indicator value may be part ofinformation conveyed in a regular downlink control sub-channel segmentused for assigning uplink traffic channel segments, and using coherentmodulation with a QPSK modulation constellation.

In some embodiments, transmitted non-zero modulation symbol valuescorresponding to the first type modulation method are transmitted at ahigher energy level than the transmission energy level of the non-zeromodulation symbol values corresponding to the second modulation method.In some embodiments, the per-tone relative transmission power differenceis at least 6 dBs, 9 dBs, or 12 dBs. In some embodiments, with regard tothe different types of downlink signals transmitted by the base station,only beacon signals are transmitted with higher per-tone relativetransmission power than first type assignment signals.

In some embodiments each first type uplink traffic channel assignment,e.g., flash type assignment, may be included as part of a messageincluding at most one first type uplink traffic channel assignment. Insome such embodiments, such a message may also include an acknowledgmentto an uplink traffic channel segment.

In some embodiments, each second type uplink traffic channel assignment,e.g., regular type assignment, may be included as part of a messageincluding at most one or two uplink traffic channel assignments. In somesuch embodiments, such a message may also include downlink trafficchannel assignment information and/or uplink traffic channelacknowledgment information.

In some embodiments messages conveying first type assignments, e.g.,using flash signaling techniques, provide more robust error protectionthan messages conveying second type assignments, e.g., using non-flashmodulation and coding. In some embodiments, some of the air linkresources used to convey a message including a first type assignment areused simultaneously by a message including a second type assignment.

FIG. 37 is a drawing of an exemplary base station 3700 implemented inaccordance with the present invention and using methods of the presentinvention. Exemplary base station 3700 is sometimes referred to as anaccess node as it provides access to the network for wireless terminals,e.g., mobile nodes. In some embodiments base station 3700 communicateswith WTs via OFDM uplink and downlink signaling. Base station 3700includes a receiver 3702, a transmitter 3704, a processor 3706, I/Ointerface 3708 and memory 3710 coupled together via a bus 3712 overwhich the various elements may interchange data/information.

Receiver 3702 is coupled to receive antenna 3703 via which the BS canreceive uplink signals from WTs including resource request messages anduplink traffic channel segment signals. Receiver 3702 includes decoder3714 for decoding received uplink signals.

Transmitter 3704 is coupled to transmit antenna 3705 via which the BScan transmit downlink signals to WTs including assignment signals, theassignment signals including maximum uplink rate option indicatorinformation. Transmitter 3704 includes an encoder module 3716 forencoding signals prior to transmission. In some embodiments, the sameantenna is used for both receiver 3702 and transmitter 3704. Transmitter3704 also includes a 1^(st) modulation module 3715 and a 2^(nd)modulation module 3717. 1^(st) modulation module 3715 is used to module1^(st) type assignment signals, e.g., flash assignment signals, fromfirst type assignment module 3738 using a first type of modulation,e.g., a non-coherent modulation scheme. 2^(nd) modulation module 3717 isused to module 2^(nd) type assignment signals, e.g., regular typeassignment signals, from second type assignment module 3740 using asecond type of modulation, e.g., a coherent modulation scheme using forexample, a QPSK constellation. In some embodiments, for the non-zeromodulation symbols of a first type assignment signal the per toneaverage power is higher than the per tone average power of the non-zeromodulation symbols of a second type assignment signal.

I/O interface 3708 provides an interface to other network nodes, e.g.,other base stations, routers, home agent nodes, AAA server nodes, etc.,and/or the Internet. I/O interface 3708 provides connectivity, via abackhaul network, for wireless terminals using BS 3700 as their point ofnetwork attachment, to other peer nodes located in other wireless cellsin the system and using a different BS as their point of networkattachment.

Memory 3710 includes routines 3718 and data/information 3720. Theprocessor 3706, e.g., a CPU, executes the routines 3718 and uses thedata/information 3720 in memory 3710 to control the operation of thebase station 3700 and implement the methods of the present invention.

Routines 3718 include communications routines 3722 and base stationcontrol routine 3724. Communications routines 3722 implement the variouscommunications protocols used by BS 3700. Base station control routine3724 includes scheduling module 3726, assignment generation module 3728,maximum uplink rate option indicator selection module 3730, transmissioncontrol module 3732, receiver control module 3734 and I/O interfacemodule 3736.

Scheduling module 3726, e.g., a scheduler, schedules uplink and downlinksegments to wireless terminals including uplink traffic channelsegments. Assignment generation module 3728 generates assignment signalsto be transmitted, e.g., an uplink assignment including an assignment ofan uplink traffic channel segment to a WT and a maximum uplink rateoption indicator value indicating a maximum uplink rate option to beused by the wireless terminal to which the segment is assigned indetermining an actual uplink data transmission rate to be used whentransmitting into the uplink traffic channel communications segmentcorresponding to the assignment. Assignment generation module 3728includes a first type assignment module 3738 and a second typeassignment module 3740. First type assignment module 3738 is used forgenerating assignments of a first type, e.g., flash type assignments,where at most one uplink traffic channel segment assignment is includedin a flash assignment message, a one bit field conveying the maximumuplink rate option indicator is used, and a non-coherent modulationmethod is used. Second type assignment module 3740 is used forgenerating assignments of a second type, e.g., regular type assignments,where one or two uplink traffic channel segment assignments are includedin an assignment message, for each uplink assigned segment a three bitfield conveys the maximum rate option indicator, and a coherentmodulation method is used.

Transmission control module 3732 controls transmitter 3704 operationsincluding controlling the transmission of assignments including maximumrate indicators, e.g., first types of assignments including first typemaximum rate indicators and second types of assignments including secondtype maximum rate indicators, according to a predetermined periodictransmission schedule having a fixed timing relationship to the uplinktraffic channel segments being assigned. In some embodiments, the uplinktraffic channel is partitioned into a number of indexed uplink trafficchannel segments, and some are associated with first type assignmentswhile others are associated with second type assignments.

Receiver control module 3734 controls operations of receiver 3702. I/Ointerface control module 3736 controls operation of I/O interface 3708.

Data/information 3720 includes WT data/information 3742, received uplinkresource request messages 3744, uplink segment assignment messages(uplink segment assignment message 1 3746, . . . , uplink segmentassignment message X 3748), received uplink traffic channel segmentinformation (received uplink traffic channel segment 1 information 3750,. . . , received uplink traffic channel segment Y information 3752), andsystem data/information 3754. WT data/information 3742 includes aplurality of sets of WT data/information, e.g., corresponding to WTscurrently registered with BS 3700 (WT 1 data/information 3755, WT Ndata/information 3756). WT 1 data/info 3755 includes user data 3757,e.g., user data corresponding to voice, video, text, files, etc., WTidentification information 3758, e.g., a BS assigned WT identifier,device/session/resource info 3759, e.g., device identificationinformation of WT 1, session information identifying peer nodes androuting information, and uplink and downlink traffic channel segmentsassigned to WT 1. WT 1 data/info 3755 also includes an estimate ofuplink transmit data 3760 corresponding to WT 1, e.g., based on receivedresource requests and allocated uplink traffic channel segmentassignments, and, if assigned, one or more sets of uplink assignedsegment information (uplink assigned segment 1 information 3761, . . . ,uplink assigned segment Z information 3762). Uplink assigned segment 1information 3761 includes segment identification information 3763,maximum uplink data rate indicator information 3764, received uplinksegment data 3765, and uplink data rate used information 3766. Segmentidentification information 3763 is, e.g., an uplink segment indexidentifier identifying the uplink segment within the uplink timing andfrequency structure. Maximum uplink data rate indicator information 3764includes, e.g., a maximum uplink rate option, an assignment type, and anindicator value. Receive uplink segment data 3765 includes the codedand/or decoded user data corresponding to the uplink traffic channelsegment. Uplink data rate used option 3766 is the uplink data rate whichthe WT used, e.g., WT selected to use, for the uplink traffic channelsegment, the rate used being less than or equal to the maximum uplinkdata rate indicated by information 3764 and the WT used rate beingrecovered by the BS from the received uplink traffic channel segmentsignals.

Received uplink resource request messages 3744 are received messagesfrom WTs for uplink traffic channel segments, e.g., requesting uplinktraffic channel segments or indicating amounts of uplink data needed tobe communicated. In some embodiments, some of the uplink segmentassignment messages 3746, 3748 have different formats, e.g., with first,e.g., flash type, and second, e.g., regular type, of assignments havingdifferent formats. In some embodiments, some of the second type ofassignments messages have different formats, e.g., with one or twouplink segment assignments being included in a message. Uplink segmentassignment message 3746 includes assignment 1 identification information3767 and a corresponding maximum uplink rate option indicator value3768, indicating the maximum uplink rate option that the assigned WT mayuse for the corresponding uplink traffic channel segment. In someembodiments, at least some of the assignments messages includeassignments for more than one uplink traffic channel segment. Forexample, uplink segment assignment message 1 may include assignment n IDinformation 3769 and corresponding assignment n maximum uplink rateoption indicator value 3770. Received uplink traffic channel segment 1information 3750 includes user data 3772 and corresponding data rateinformation 3774, e.g., identifying the data rate used for the segmentwhere the data rate used identifies the coding rate and the modulationmethod used for the user data of the segment.

System data/information 3754 includes uplink and downlink timing andfrequency structure information 3701, maximum uplink data rate optionindicator information 3779, and uplink data rate option information3780. Uplink and downlink timing and frequency structure information3701 includes uplink traffic channel segment information 3775 andtransmission scheduling information 3776. Uplink traffic segmentinformation 3775 includes tone information 3777 and timing information3778. Each communications segment, e.g., each uplink OFDM uplink trafficchannel communication segment, includes multiple tones used for aplurality of OFDM symbol transmission time periods. In some embodiments,each uplink traffic channel segment in the uplink timing and frequencystructure uses predetermined logical tones which are frequency hopped inaccordance with a predetermined uplink tone hopping sequence. Each ofthe uplink traffic channel segments, in the uplink timing and frequencystructure has a predetermined duration. In some embodiments, at leastsome uplink traffic channel segments have different predetermineddurations. In some embodiments, each of the uplink traffic channelsegments in the uplink timing and frequency structure has the samenumber of basic transmission units, e.g., tone-symbols. For example, onetype of uplink traffic channel segment may be allocated a first numberof tones (N1) for a first number of OFDM transmission time intervals(N2), and a second type of uplink traffic channel segment may beallocated a second number of tones (N3) for a second number of OFDMtransmission time intervals (N4), where N1, N2, N3, N4 are positiveintegers, where N1>N3, where N4>N2, and where N1×N2=N3×N4. Transmissionscheduling information 3776 includes information identifying apredetermined periodic transmission schedule having a fixed timingrelationship between each of the uplink traffic channel segments and theassignments.

Maximum uplink data rate option indicator information 3779 includes a1^(st) type of maximum uplink data rate option indicator information3781 and a 2^(nd) type of maximum uplink data rate option indicatorinformation 3782. 1^(st) type information 3781 corresponding to firsttype assignment module 3738 and 1^(st) modulation module 3715 includes aplurality of rate option information (rate 1 information 3783, . . . ,rate M info 3784, a number of bits 3785, modulation method information3786, and a maximum uplink data rate option indicator table 3787. Forexample, the WT may support 8 uplink rate options, the number of bits3785 for a 1^(st) type maximum rate option indicator field may be onepermitting two rates to be identified, e.g., rate 1 information with anindicator bit value of zero may correspond to rate option 3, anintermediate rate option level, and rate M information with an indicatorbit value of 1 may correspond to rate option 7, the highest rate option;the modulation method information may identify a non-coherent modulationmethod using a combination of zero and non-zero QPSK modulation symbolsmapped to the assignment segment tone-symbols. First rate optionindicator table 3787, including at least some of information 3783, 3784,3785, 3786, is included in some embodiments, and is used by first typeassignment module 3738 in generating first type indicator assignments.

2^(nd) type information 3782 corresponding to second type assignmentmodule 3740 and 2^(nd) modulation module 3717 includes a plurality ofrate option information (rate 1 information 3788, . . . , rate m info3789, a number of bits 3790, modulation method information 3791, and amaximum uplink data rate option indicator table 3792. For example, theWT may support 8 uplink rate options, the number of bits for a 2^(nd)type maximum rate option indicator field may be three permitting each ofthe supported uplink rates to be identified, e.g., rate 1 informationwith indicator bit values of (000) may correspond to rate option 0 whichis the lowest rate option, rate information 2 with indicator bit valuesof (001) may correspond to rate option 1, . . . , rate option m withindicator bit values of (111) may correspond to rate option 7 which isthe highest rate option; the modulation method information may identifya conventional coherent modulation method, e.g., using a QPSK modulationconstellation. Second rate option indicator table 3792, including atleast some of information 3788, 3789, 3790, 3791, is included in someembodiments, and is used by second type assignment module 3740 ingenerating second type indicator assignments. In some embodiments,second rate option indicator table 3792 includes each supported rateoption.

Uplink data rate option information 3780 includes informationcorresponding to each of the uplink data rate options supported by theWT (rate 1 information 3793, . . . , rate N option information 3794) foruplink traffic channel segment communications. Each set of data rateoption information (3793, 3794) corresponds to a coding rate andmodulation method used. In some embodiments, at least two of the datarate options use different coding rates. In some embodiments, at leasttwo of the data rate options use different modulation methods, e.g.,QPSK and QAM16.

This application is directed to numerous methods and apparatus which canbe used to implement a communications system. In various embodiments oneor more features described with respect to an exemplary embodiment maybe combined with one or more features described with respect to anotherexemplary embodiment.

While described in the context of an OFDM system, many of the methodsand apparatus of the present invention, are applicable to a wide rangeof communications systems including many non-OFDM and/or non-cellularsystems.

In various embodiments nodes described herein are implemented using oneor more modules to perform the steps corresponding to one or moremethods of the present invention, for example, selecting a maximumuplink data transmission rate, transmitting a maximum uplink data rateindicator, estimating interference levels, selecting an uplink data rateto use, encoding uplink data rate information with user data/info,recovering uplink data rate information, etc. In some embodimentsvarious features of the present invention are implemented using modules.Such modules may be implemented using software, hardware or acombination of software and hardware. Many of the above describedmethods or method steps can be implemented using machine executableinstructions, such as software, included in a machine readable mediumsuch as a memory device, e.g., RAM, floppy disk, etc. to control amachine, e.g., general purpose computer with or without additionalhardware, to implement all or portions of the above described methods,e.g., in one or more nodes. Accordingly, among other things, the presentinvention is directed to a machine-readable medium including machineexecutable instructions for causing a machine, e.g., processor andassociated hardware, to perform one or more of the steps of theabove-described method(s).

Numerous additional variations on the methods and apparatus of thepresent invention described above will be apparent to those skilled inthe art in view of the above description of the invention. Suchvariations are to be considered within the scope of the invention. Themethods and apparatus of the present invention may be, and in variousembodiments are, used with CDMA, orthogonal frequency divisionmultiplexing (OFDM), and/or various other types of communicationstechniques which may be used to provide wireless communications linksbetween access nodes and mobile nodes. In some embodiments the accessnodes are implemented as base stations which establish communicationslinks with mobile nodes using OFDM and/or CDMA. In various embodimentsthe mobile nodes are implemented as notebook computers, personal dataassistants (PDAs), or other portable devices includingreceiver/transmitter circuits and logic and/or routines, forimplementing the methods of the present invention.

1. A method of operating a base station in a communications system totransmit assignment information indicating assignment of uplinkcommunications segments, each segment having a predetermined duration,the method comprising: generating a first segment assignment signalassigning a first communications segment to a wireless terminal, thefirst segment assignment signal including a first maximum uplink rateoption indicator value having a first number of bits and indicating afirst maximum uplink rate option corresponding to a plurality of rateoptions available to the wireless terminal in determining the actualuplink transmission rate to be used when transmitting in the firstcommunications segment; transmitting said first segment assignmentsignal to the wireless terminal over a first wireless assignmentchannel; generating a second segment assignment signal assigning asecond communications segment to said wireless terminal, the secondsegment assignment signal including a second maximum uplink rate optionindicator value, said second maximum uplink rate option indicator valuehaving a second number of bits which is more than said first number ofbits and indicating a second maximum uplink rate option corresponding toa plurality of rate options available to the wireless terminal indetermining the actual uplink transmission rate to be used whentransmitting in the second communications segment; and transmitting thesecond segment assignment signal to said wireless terminal over a secondwireless assignment channel.
 2. The method of claim 1, wherein saidsecond segment assignment signal further includes a wireless terminalidentifier which identifies said wireless terminal to which said secondcommunications segment is assigned; and wherein said communicationssegments are OFDM communications segments including multiple tones usedfor a plurality of OFDM symbol transmission time periods.
 3. The methodof claim 1, wherein said system supports a fixed number of differentuplink rate options, the method further comprising: selecting a saidfirst maximum rate option indicator value, prior to transmitting saidfirst segment assignment signal, said value being selected from a set ofvalues including at least one value corresponding to the highest uplinkrate option supported by said system and another value corresponding toan intermediate rate option supported by said system; and wherein saidfirst maximum unlink rate option indicator value is a single bit value.4. A method of operating a base station in a communications systemsupporting a fixed number of different uplink rate options andtransmitting assignment information indicating assignment of uplink OFDMcommunications segments, each segment having a predetermined durationand including multiple tones used for a plurality of OFDM symboltransmission time periods, the method comprising: selecting a firstmaximum rate option indicator value of a first type and including afirst number of bits from a set of values including at least one valuecorresponding to the highest uplink rate option supported by said systemand another value corresponding to an intermediate rate option supportedby said system; transmitting over a wireless communications channel afirst assignment including said first maximum uplink rate optionindicator value of said first type indicating a first maximum uplinkrate option to be used by a wireless terminal in determining the actualuplink transmission rate to be used when transmitting in a first OFDMcommunications segment corresponding to said first assignment; andtransmitting over said wireless communications channel a secondassignment including a second maximum uplink rate option indicator of asecond type, said second type maximum uplink rate option indicator valueincluding more bits than said first type allowing for more maximumuplink rate options to be specified than said first type indicator. 5.The method of claim 4, wherein the first type indicator includes at mostone bit and the second type indicator includes at least 3 bits.
 6. Themethod of claim 5, wherein transmitting the second type includes using adifferent modulation method than a modulation method used to transmitthe first type maximum uplink rate indicator values.
 7. The method ofclaim 6, wherein the base station transmits assignments including maxrate indicators of the first type according to a predetermined periodictransmission schedule having a fixed timing relationship to the uplinksegments being assigned.
 8. The method of claim 7, wherein saidcommunications segments are traffic channel segments.
 9. The methodclaim 1 further comprising: storing first and second maximum rate optionindicator tables; using said first maximum rate option indicator tablefor assignments of a first type, assignments of the first type beingtransmitted over said first wireless assignment channel; using saidsecond maximum rate option indicator table for assignments of a secondtype, assignments of the second type being transmitted over the secondwireless assignment channel.
 10. The method of claim 9, whereinassignment signals transmitted over said first wireless assignmentchannel are generated using non-coherent modulation, said step ofgenerating said first assignment signal including performingnon-coherent modulation; and wherein assignment signals transmitted oversaid second wireless assignment channel are generated using coherentmodulation, said step of generating said second assignment signalincluding performing coherent modulation.
 11. A base station for use ina communications system, comprising: a first type assignment generationmodule for generating a first segment assignment signal assigning afirst communications segment to a wireless terminal, the first segmentassignment signal including a first maximum uplink rate option indicatorvalue having a first number of bits and indicating a first maximumuplink rate option corresponding to a plurality of rate optionsavailable to the wireless terminal in determining an actual uplinktransmission rate to be used when transmitting into the firstcommunications segment; a second type assignment generation module forgenerating a second segment assignment signal assigning a secondcommunications segment to said wireless terminal, the second segmentassignment signal including a second maximum uplink rate optionindicator value, said second maximum uplink rate option indicator valuehaving a second number of bits which is more than said first number ofbits and indicating a second maximum uplink rate option corresponding toa plurality of rate options available to the wireless terminal indetermining the actual uplink transmission rate to be used whentransmitting in the second communications segment; and a transmitter fortransmitting assignment information indicating assignment of uplinkcommunications segments, each segment having a predetermined durationover a wireless communications channel, said transmitter beingconfigured to transmit said first assignment signal to said wirelessterminal over a first wireless assignment channel and transmit saidsecond assignment signal to said wireless terminal over a secondwireless assignment channel.
 12. The base station of claim 11, whereinsaid transmitter is an OFDM transmitter; and wherein said communicationssegments are OFDM communications segments including multiple tones usedfor a plurality of OFDM symbol transmission time periods.
 13. The basestation of claim 12, wherein said system supports a fixed number ofdifferent uplink rate options, the base station further comprising: aselection module for selecting said first maximum rate option indicatorvalue, prior to transmitting said first assignment signal, said valuebeing selected from a set of values including at least one valuecorresponding to the highest uplink rate option supported by said systemand another value corresponding to an intermediate rate option supportedby said system; and wherein said first maximum uplink rate optionindicator value is a single bit value.
 14. A base station for use in acommunications system supporting a fixed number of different uplink rateoptions, comprising: an OFDM transmitter for transmitting assignmentinformation indicating assignment of uplink OFDM communicationssegments, each segment having a predetermined duration over a wirelesscommunications channel and including multiple tones used for a pluralityof OFDM symbol transmission time periods; a selection module forselecting a first maximum rate option indicator value of a first typeand including a first number of bits from a set of values including atleast one value corresponding to the highest uplink rate optionsupported by said system and another value corresponding to anintermediate rate option supported by said system; and an assignmentgeneration module for generating assignment signals to be transmitted,said assignment signals including at least a first assignment includinga first maximum uplink rate option indicator value indicating a firstmaximum uplink rate option to be used by a wireless terminal indetermining an actual uplink transmission rate to be used whentransmitting into a first communications segment corresponding to saidfirst assignment, and a second assignment including a second maximumuplink rate option indicator of a second type, said second type maximumuplink rate option indicator value including more bits than said firsttype allowing for more maximum uplink rate options to be specified thansaid first type indicator.
 15. The base station of claim 14, wherein thefirst type indicator includes at most one bit and the second typeindicator includes at least 3 bits.
 16. The base station of claim 15,wherein said transmitter includes first and second modulation modules,the first modulation module being used to modulate the first assignmentsignal, the second modulation module being used to modulate the secondassignment signal, the first and second modulation modules performingdifferent types of modulation.
 17. The base station of claim 16, whereinthe base station further includes: a transmission control module whichcontrols transmission of assignments including max rate indicators ofthe first type according to a predetermined periodic transmissionschedule having a fixed timing relationship to the uplink segments beingassigned.
 18. The base station of claim 17, wherein said communicationssegments are traffic channel segments.
 19. The base station of claim 11further comprising: memory for storing first and second maximum rateoption indicator tables; and wherein said first type assignmentgeneration module uses said first maximum rate option indicator tablefor generating assignments of a first type, assignments of the firsttype being transmitted over said first wireless assignment channel, saidsecond type assignment generation module uses said second maximum rateoption indicator table for generating assignments of a second type,assignments of the second type being transmitted over the secondwireless assignment channel.
 20. The base station of claim 19, whereinassignment signals transmitted over said first wireless assignmentchannel are generated using non-coherent modulation; and whereinassignment signals transmitted over said second assignment channel aregenerated using coherent modulation.
 21. A base station for use in acommunications system, comprising: first type assignment generationmeans for generating a first segment assignment signal assigning a firstcommunications segment to a wireless terminal, the first segmentassignment signal including a first maximum uplink rate option indicatorvalue having a first number of bits and indicating a first maximum uplink rate option corresponding to a plurality of rate options availableto the wireless terminal in determining an actual uplink transmissionrate to be used when transmitting into the first communications segment;second type assignment generation means for generating a second segmentassignment signal assigning a second communications segment to saidwireless terminal, the second segment assignment signal including asecond maximum uplink rate option indicator value, said second maximumunlink rate option indicator value having a second number of bits whichis more than said first number of bits and indicating a second maximumuplink rate option corresponding to a plurality of rate optionsavailable to the wireless terminal in determining the actual uplinktransmission rate to be used when transmitting in the secondcommunications segment; and transmitter means for transmittingassignment information indicating assignment of uplink communicationssegments, each segment having a predetermined duration over a wirelesscommunications channel, said transmitter means being configured totransmit said first assignment signal to said wireless terminal over afirst wireless assignment channel and transmit said second assignmentsignal to said wireless terminal over a second wireless assignmentchannel.
 22. The base station of claim 21, wherein said transmittermeans is an OFDM transmitter means; and wherein said communicationssegments are OFDM communications segments including multiple tones usedfor a plurality of OFDM symbol transmission time periods.
 23. The basestation of claim 22, wherein said system supports a fixed number ofdifferent uplink rate options, the base station further comprising:selection means for selecting said first maximum rate option indicatorvalue, prior to transmitting said first segment assignment signal saidvalue being selected from a set of values including at least one valuecorresponding to the highest uplink rate option supported by said systemand another value corresponding to an intermediate rate option supportedby said system; and wherein said first maximum unlink rate optionindicator value is a single bit value.
 24. A device comprising aprocessor configured to control a base station in a communicationssystem to transmit assignment information indicating assignment ofuplink communications segments, each segment having a predeterminedduration, the processor being configured to control said base stationto: generate a first segment assignment signal assigning a firstcommunications segment to a wireless terminal, the first segmentassignment signal including a first maximum uplink rate option indicatorvalue having a first number of bits and indicating a first maximumuplink rate option corresponding to a plurality of rate optionsavailable to the wireless terminal in determining the actual uplinktransmission rate to be used when transmitting in the firstcommunications segment; transmit said first segment assignment signal tothe wireless terminal over a first wireless assignment channel; generatea second segment assignment signal assigning a second communicationssegment to said wireless terminal, the second segment assignment signalincluding a second maximum uplink rate option indicator value, saidsecond maximum uplink rate option indicator value having a second numberof bits which is more than said first number of bits and indicating asecond maximum uplink rate option corresponding to a plurality of rateoptions available to the wireless terminal in determining the actualuplink transmission rate to be used when transmitting in the secondcommunications segment; and transmit the second segment assignmentsignal to said wireless terminal over a second wireless assignmentchannel.
 25. The device of claim 24, wherein said communicationssegments are OFDM communications segments including multiple tones usedfor a plurality of OFDM symbol transmission time periods.
 26. The deviceof claim 25, wherein said system supports a fixed number of differentuplink rate options, the processor being further configured to controlsaid base station to: select said first maximum rate option indicatorvalue, prior to transmitting said first segment assignment signal, saidvalue being selected from a set of values including at least one valuecorresponding to the highest uplink rate option supported by said systemand another value corresponding to an intermediate rate option supportedby said system; and wherein said first maximum uplink rate optionindicator value is a single bit value.
 27. A machine readable mediumembodying machine executable instructions for controlling a base stationin a communications system to transmit assignment information indicatingassignment of uplink communications segments, each segment having apredetermined duration, the machine readable medium comprising:instructions for causing the base station to generate a first segmentassignment signal assigning a first communications segment to a wirelessterminal, the first segment assignment signal including a first maximumuplink rate option indicator value having a first number of bits andindicating a first maximum uplink rate option corresponding to aplurality of rate options available to the wireless terminal indetermining the actual uplink transmission rate to be used whentransmitting in the first communications segment; instructions forcausing the base station to transmit said first segment assignmentsignal to the wireless terminal over a first wireless assignmentchannel; instructions for causing the base station to generate a secondsegment assignment signal assigning a second communications segment tosaid wireless terminal, the second segment assignment signal including asecond maximum uplink rate option indicator value, said second maximumuplink rate option indicator value having a second number of bits whichis more than said first number of bits and indicating a second maximumuplink rate option corresponding to a plurality of rate optionsavailable to the wireless terminal in determining the actual uplinktransmission rate to be used when transmitting in the secondcommunications segment; and instructions for causing the base station totransmit the second segment assignment signal to said wireless terminalover a second wireless assignment channel.
 28. The machine readablemedium of claim 27, wherein said communications segments are OFDMcommunications segments including multiple tones used for a plurality ofOFDM symbol transmission time periods.
 29. The machine readable mediumof claim 28, wherein said system supports a fixed number of differentuplink rate options, and wherein the machine readable medium furthercomprises: instructions for causing the base station to select saidfirst maximum rate option indicator value, prior to transmitting saidfirst segment assignment signal, said value being selected from a set ofvalues including at least one value corresponding to the highest uplinkrate option supported by said system and another value corresponding toan intermediate rate option supported by said system; and wherein saidfirst maximum uplink rate option indicator value is a single bit value.